Electrophotographic light-sensitive material

ABSTRACT

An electrophotographic light-sensitive material which has improved electrostatic characteristics and image forming performance and is excellent particularly in reproducibility of highly accurate image using a liquid developer and image forming performance upon a scanning exposure system using a laser beam of a low power. 
     The electrophotographic light-sensitive material contains, as a binder resin, at least one resin (A) which has a weight average molecular weight of from 1×10 3  to 2×10 4  and contains not less than 30% by weight of a polymer component of the formula (I) and from 0.5 to 15% by weight of a specified polar group-containing polymer component and at least one resin (B) which is an AB block copolymer having a weight average molecular weight of from 3×10 4  to 1×10 6  and comprising an A block containing a specified polar group-containing polymer component and a B block containing a polymer component of the formula (I). ##STR1## wherein a 1  and a 2  : hydrogen, halogen, a cyano group, a hydrocarbon group, --COOR 4  or --COOR 4  bonded via a hydrocarbon group (R 4  : hydrocarbon group), and R 3  : a hydrocarbon group.

TECHNICAL FIELD

The present invention relates to an electrophotographic light-sensitivematerial, and more particularly to an electrophotographiclight-sensitive material which is excellent in electrostaticcharacteristics and moisture resistance.

TECHNICAL BACKGROUND

An electrophotographic light-sensitive material may have variousstructures depending upon the characteristics required or anelectrophotographic process to be employed.

Typical electrophotographic light-sensitive materials widely employedcomprise support having provided thereon at least one photoconductivelayer and, if necessary, an insulating layer on the surface thereof.

The electrophotographic light-sensitive material comprising a supportand at least one photoconductive layer formed thereon is used for theimage formation by an ordinary electrophotographic process includingelectrostatic charging, imagewise exposure, development, and, ifdesired, transfer.

Furthermore, a process using an electrophotographic light-sensitivematerial as an offset master plate precursor for direct plate making iswidely practiced. In particular, a direct electrophotographiclithographic plate has recently become important as a system forprinting in the order of from several hundreds to several thousandsprints having a high image quality.

Under these circumstances, binder resins which are used for forming thephotoconductive layer of an electrophotographic light-sensitive materialare required to be excellent in the film-forming properties bythemselves and the capability of dispersing photoconductive powdertherein. Also, the photoconductive layer formed using the binder resinis required to have satisfactory adhesion to a base material or support.Further, the photoconductive layer formed by using the binder resin isrequired to have various excellent electrostatic characteristics such ashigh charging capacity, small dark decay, large light decay, and lessfatigue due to prior light-exposure and also have an excellent imageforming properties, and the photoconductive layer stably maintains theseelectrostatic properties in spite of the fluctuation in humidity at thetime of image formation.

Further, extensive studies have been made for lithographic printingplate precursors using an electrophotographic light-sensitive material,and for such a purpose, binder resins for a photoconductive layer whichsatisfy both the electrostatic characteristics as an electrophotographiclight-sensitive material and printing properties as a printing plateprecursor are required.

It has been found that the chemical structure of binder resin used in aphotoconductive layer which contains at least an inorganicphotoconductive substance, a spectral sensitizing dye and a binder resinhas a great influence upon the electrostatic characteristics as well assmoothness of the photoconductive layer. Among the electrostaticcharacteristics, dark charge retention rate (D.R.R.) andphotosensitivity are particularly affected.

Techniques for improvements in smoothness and electrostaticcharacteristics of a photoconductive layer by using a resin having a lowmolecular weight and containing an acidic group in a polymer componentconstituting the polymer main chain or at one terminal of the polymermain chain are described, for example, in JP-A-63-217354 (the term"JP-A" as used herein means an "unexamined published Japanese PatentApplication"), JP-A-1-70761, JP-A-2-64547, JP-A-2-93540 andJP-A-3-181948.

Further, techniques for improving a mechanical strength of aphotoconductive layer by using the above described low molecular weightresin together with a medium to high molecular weight resin aredescribed, for example, in JP-A-64-564, JP-A-63-220149, JP-A-63-220148,JP-A-1-280761, JP-A-l-116643, JP-A-l-169455, JP-A-2-69758,JP-A-2-167551, JP-A-1-211766, JP-A-2-34859, JP-A-2-68561, JP-A-2-135455,JP-A-2-34860, JP-A-2-96766, JP-A-2-40660, JP-A-2-53064, JP-A-2-103056,JP-A-2-56558, JP-A-3-29954, JP-A-3-75753, JP-A-3-77954, JP-A-3-42665,JP-A-3-92861, JP-A-3-92862, JP-A-3-53257, JP-A-3-92863, JP-A-3-206464,and JP-A-3-225344.

PROBLEMS TO BE SOLVED BY THE INVENTION

However, it has been found that, even in a case of using these resins ora combination of these resins, it is yet insufficient to keep the stableperformance in the case of greatly fluctuating the ambient conditionsfrom high-temperature and high-humidity to low-temperature andlow-humidity. In particular, in a scanning exposure system using asemiconductor laser beam, the exposure time becomes longer and alsothere is a restriction on the exposure intensity as compared to aconventional overall simultaneous exposure system using a visible light,and hence a higher performance has been required for the electrostaticcharacteristics, in particular, the dark charge retentioncharacteristics and photosensitivity.

Further, when the scanning exposure system using a semiconductor laserbeam is applied to hitherto known light-sensitive materials forelectrophotographic lithographic printing plate precursors, variousproblems may occur in that the difference between E_(1/2) and E_(1/10)is particularly large and the contrast of the duplicated image isdecreased. Moreover, it is difficult to reduce the remaining potentialafter exposure, which results in severe fog formation in duplicatedimage, and when employed as offset masters, edge marks of originalspasted up appear on the prints, in addition to the insufficientelectrostatic characteristics described above.

Moreover, it has been desired to develop a technique which canfaithfully reproduce highly accurate images of continuous gradation aswell as images composed of lines and dots using a liquid developer.However, the above-described known techniques are still insufficient tofulfill such a requirement. Specifically, in the known technique, theimproved electrostatic characteristics which are achieved by means ofthe low molecular weight resin may be sometimes deteriorated by using ittogether with the medium to high molecular weight resin. In fact, it hasbeen found that an electrophotographic light-sensitive material having aphotoconductive layer wherein the above described known resins are usedin combination may cause a problem on reproducibility of the abovedescribed highly accurate image (particularly, an image of continuousgradation) or on image forming performance in case of using a scanningexposure system with a laser beam of low power.

The present invention has been made for solving the problems ofconventional electrophotographic light-sensitive materials as describedabove.

An object of the present invention is to provide an electrophotographiclight-sensitive material having stable and excellent electrostaticcharacteristics and giving clear good images even when the ambientconditions during the formation of duplicated images are fluctuated tolow-temperature and low-humidity or to high-temperature andhigh-humidity.

Another object of the present invention is to provide a CPCelectrophotographic light-sensitive material having excellentelectrostatic characteristics and showing less environmental dependency.

A further object of the present invention is to provide anelectrophotographic light-sensitive material effective for a scanningexposure system using a semiconductor laser beam.

A still further object of the present invention is to provide anelectrophotographic lithographic printing plate precursor havingexcellent electrostatic characteristics (in particular, dark chargeretention characteristics and photosensitivity), capable of reproducinga faithfully duplicated image to the original (in particular, a highlyaccurate image of continuous gradation), forming neither overallbackground stains nor dotted background stains of prints, and showingexcellent printing durability.

Other objects of the present invention will become apparent from thefollowing description.

DISCLOSURE OF THE INVENTION

It has been found that the above described objects of the presentinvention are accomplished by an electrophotographic .light-sensitivematerial having a photoconductive layer containing at least an inorganicphotoconductive substance, a spectral sensitizing dye and a binderresin, wherein the binder resin comprises at least one resin (A) shownbelow and at least one resin (B) shown below.

Resin (A):

A resin having a weight average molecular weight of from 1×10³ to 2×10⁴and containing not less than 30% by weight of a polymer component.corresponding to a repeating unit represented by the general formula(I) described below and from 0.5 to 15% by weight of a polymer componentcontaining at least one polar group selected from --PO₃ H₂, --SO₃ H,--COOH, ##STR2## (wherein R¹ represents a hydrocarbon group or --OR²(wherein R² represents a hydrocarbon group)) and a cyclic acidanhydride-containing group. ##STR3## (wherein a¹ and a² each representsa hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group,--COOR⁴ or --COOR⁴ bonded via a hydrocarbon group (wherein R⁴ representsa hydrocarbon group); and R³ represents a hydrocarbon group). Resin (B):

An AB block copolymer having a weight average molecular weight of from3×10⁴ to 1×10⁶ and containing an A block comprising a polymer componentcontaining at least one polar group selected from the specific polargroups as described in the resin (A) above and a B block comprising apolymer component represented by the general formula (I) as described inthe resin (A) above, wherein the A block contains the polymer componentcontaining the polar group in an amount of from 0.05 to 10% by weightbased on the copolymer and the B block contains the polymer componentrepresented by the general formula (I) in an amount not less than 30% byweight based on the copolymer.

In short, the binder resin which can be used in the present inventioncomprises at least a low molecular weight polymer containing a polymercomponent represented by the general formula (I) described above and apolymer component containing the specified polar group described above(resin (A)) and an AB block copolymer comprising an A block comprising apolymer component containing the specified polar group described aboveand a B block comprising a polymer component represented by the generalformula (I) described above (resin (B)).

As a result of various investigations, it has been found that in theknown technique wherein the low molecular weight resin containing apolar group is used together with the medium to high molecular weightresin, the improved electrostatic characteristics achieved by the lowmolecular weight resin are sometimes deteriorated by the medium to highmolecular weight resin used together as described above. Further, it hasbecome apparent that an appropriate action of medium to high molecularweight resin on the interaction between the photoconductive substance,spectral sensitizing dye and low molecular weight resin in thephotoconductive layer is an unexpectedly important factor.

It has been found that the above described objects can be effectivelyachieved by using the AB block copolymer comprising an A blockcontaining the polar group and a B block containing no polar groupaccording to the present invention as a medium to high molecular weightresin to be used together with the low molecular weight resin (A)containing the polar group.

It is presumed that the electrostatic characteristics are stablymaintained at a high level as a result of synergistic effect of theresin (A) and resin (B) according to the present invention whereinparticles of inorganic photoconductive substance are sufficientlydispersed without the occurrence of aggregation, a spectral sensitizingdye and a chemical sensitizer are sufficiently adsorbed on the surfaceof particles of inorganic photoconductive substance, and the binderresin is sufficiently adsorbed to excessive active sites on the surfaceof the inorganic photoconductive substance to compensate the traps.

More specifically, the low molecular weight resin (A) containing thespecific polar group has the important function in that the resin issufficiently adsorbed on the surface of particles of the inorganicphotoconductive substance to disperse uniformly and to restrain theoccurrence of aggregation due to its short polymer chain and in thatadsorption of the spectral sensitizing dye on the inorganicphotoconductive substance is not disturbed.

Further, by using the medium to high molecular weight AB block copolymercomprising an A block containing the specific polar group and a B blockwhich does not contain the specific polar group, mechanical strength ofthe photoconductive layer is remarkably increased. This is believed tobe based on that the A block portion of the resin has a weak interactionwith the particles of photoconductive substance compared with the resin(A) and that the polymer chains of the B block portions of the resinsintertwine each other.

Moreover, according to the present invention the electrostaticcharacteristics are more improved in comparison with a case wherein aknown medium to high molecular weight resin is employed. This isbelieved to be based on that the resin (B) acts to control thedisturbance of adsorption of spectral sensitizing dye on the surface ofparticles of photoconductive substance due to the polar group present inthe A block portion which interacts with the particles ofphotoconductive substance.

As a result, it is presumed that the resin (B) appropriately effects oncontrolling the disturbance of adsorption of spectral sensitizing dye onthe surface of particles of photoconductive substance and theelectrophotographic interactions and increasing the strength of thephotoconductive layer in a system wherein the particles ofphotoconductive substance, spectral sensitizing dye and resin (A) arecoexistent with the resin (B), while details thereof are not clear.

This effect is especially remarkable in a case wherein polymethine dyesor phthalocyanine series pigments which are particularly effective asspectral sensitizing dyes for the region of near infrared to infraredlight are used.

When the electrophotographic light-sensitive material according to thepresent invention containing photoconductive zinc oxide as the inorganicphotoconductive substance is applied to a conventional direct printingplate precursor, extremely good water retentivity as well as theexcellent image forming performance can be obtained. More specifically,when the light-sensitive material according to the present invention issubjected to an electrophotographic process to form an duplicated image,oil-desensitization of non-image portions by chemical treatment with aconventional oil-desensitizing solution to prepare a printing plate, andprinting by an offset printing system, it exhibits excellentcharacteristics as a printing plate.

When the electrophotographic light-sensitive material according to thepresent invention is subjected to the oil-desensitizing treatment, thenon-image portions are rendered sufficiently hydrophilic to increasewater retentivity which results in remarkable increase in a number ofprints obtained. It is believed that these results are obtained by thefact that the condition is formed under which a chemical reaction forrendering the surface of zinc oxide hydrophilic upon theoil-desensitizing treatment is able to proceed easily and effectively.Specifically, zinc oxide particles are uniformly and sufficientlydispersed in the resin (A) and resin (B) used as a binder resin and thestate of binder resin present on or adjacent to the surface of zincoxide particles is proper to conduct an oil-desensitizing reaction withthe oil-desensitizing solution rapidly and effectively.

Now, the resin (A) which can be used as the binder resin for thephotoconductive layer of the electrophotographic light-sensitivematerial according to the present invention will be described in moredetail below.

The weight average molecular weight of the resin (A) is from 1×10³ to2×10⁴ and preferably from 3×10³ to 1×10⁴. The glass transition point ofthe resin (A) is preferably from -30° C. to 110° C. and more preferablyfrom -10° C. to 90° C.

If the weight average molecular weight of the resin (A) is less than1×10³ the film-forming property of the resin is lowered, thereby asufficient film strength cannot be maintained, while if the weightaverage molecular weight of the resin (A) is higher than 2×10⁴ theeffect of the present invention for obtaining stable duplicated imagesis reduced since fluctuations of dark decay retention rate andphotosensitivity of the photoconductive layer, in particular, thatcontaining a spectral sensitizing dye for sensitization in the range offrom near-infrared to infrared become somewhat large under severeconditions of high temperature and high humidity or low temperature andlow humidity.

The content of the polymer component corresponding to the repeating unitrepresented by the general formula (I) present in the resin (A) is notless than 30% by weight, preferably from 50 to 99% by weight, and thecontent of the polymer component containing the specific polar grouppresent in the resin (A) is from 0.5 to 15% by weight, preferably from 1to 10% by weight.

If the content of the polar group-containing component in the resin (A)is less than 0.5% by weight, the initial potential is low and thussatisfactory image density is hardly obtained. On the other hand, if thecontent of the polar group-containing component is larger than 15% byweight, various undesirable problems may occur, for example, thedispersibility is reduced, and further when the light-sensitive materialis used as an offset master plate, the occurrence of background stainsmay increase.

The repeating unit represented by the general formula (I) above which iscontained in the resin (A) in an amount of not less than 30% by weightwill be described in greater detail below.

In the general formula (I), a¹ and a² each preferably represents ahydrogen atom, a halogen atom (e.g., chlorine, and bromine), a cyanogroup, an alkyl group having from 1 to 4 carbon atoms (e.g., methyl,ethyl, propyl and butyl), --COOR⁴ or --COOR⁴ bonded via a hydrocarbongroup (wherein R⁴ represents an alkyl, alkenyl, aralkyl, alicyclic oraryl group which may be substituted, and specifically includes those asdescribed for R³ hereinafter). Preferably a¹ represents a hydrogen atomand a² represents a methyl group.

The hydrocarbon group in the above described --COOR⁴ group bonded via ahydrocarbon group includes, for example, a methylene group, an ethylenegroup, and a propylene group.

R³ preferably represents a hydrocarbon group having not more than 18carbon atoms, which may be substituted. The substituent for thehydrocarbon group may be any substituent other than the polar groupscontained in the polar group-containing polymer component describedabove. Suitable examples of the substituent include a halogen atom(e.g., fluorine, chlorine, and bromine), --OR⁵, --COOR⁵, and --OCOR⁵(wherein R⁵ represents an alkyl group having from 1 to 22 carbon atoms,e.g., methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl,hexadecyl, and octadecyl). Preferred examples of the hydrocarbon groupinclude an alkyl group having from 1 to 18 carbon atoms which may besubstituted (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, decyl, dodecyl, hexadecyl, octadecyl, 2-chloroethyl,2-bromoethyl, 2-cyanoethyl, 2-hydroxyethyl, 2-methoxycarbonylethyl,2-methoxyethyl, 2-ethoxyethyl, 3-hydroxypropyl and 3-bromopropyl), analkenyl group having from 2 to 18 carbon atoms which may be substituted( e. g., vinyl, allyl, 2-methyl-l-propenyl, 2-butenyl, 2-pentenyl,3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, and4-methyl-2-hexenyl), an aralkyl group having from 7 to 12 carbon atomswhich may be substituted (e.g., benzyl, phenethyl, 3-phenylpropyl,naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl,methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl anddimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclopentyl, cyclohexyl,2-cyclohexylethyl, and 2-cyclopentylethyl), and an aromatic group havingfrom 6 to 12 carbon atoms which may be substituted (e.g., phenyl,naphthyl, tolyl, xylyl, propylphenyl, butylphenyl, octylphenyl,dodecylphenyl, methoxyphenyl, ethoxyphenyl, butoxyphenyl,decyloxyphenyl, chlorophenyl, dichlorophenyl, bromophenyl, cyanophenyl,acetylphenyl, methoxycarbonylphenyl, ethoxycarbonylphenyl,butoxycarbonylphenyl, acetamidophenyl, propioamidophenyl, anddodecyloylamidophenyl).

More preferably, the polymer component corresponding to the repeatingunit represented by the general formula (I) is a methacrylate componenthaving the specific aryl group represented by the general formula (Ia)and/or (Ib) described below. The low molecular weight resin containingthe specific aryl group-containing methacrylate polymer componentdescribed above is sometimes referred to as a resin (A') hereinafter.##STR4## wherein T₁ and T₂ each represents a hydrogen atom, a halogenatom, a hydrocarbon group having from 1 to 10 carbon atoms, --COR_(a) or--COOR_(a), wherein R_(a) represents a hydrocarbon group having from 1to 10 carbon atoms; and L₁ and L₂ each represents a mere bond or alinking group containing from 1 to 4 linking atoms, which connects--COO-- and the benzene ring.

In the resin (A'), the content of the methacrylate polymer componentcorresponding to the repeating unit represented by the general formula(Ia) and/or (Ib) is suitably not less than 30% by weight, preferablyfrom 50 to 97% by weight, and the content of polymer componentcontaining the specified polar group is suitably from 0.5 to 15% byweight, preferably from 1 to 10% by weight.

In case of using the resin (A'), the electrophotographiccharacteristics, particularly, V₁₀, D.R.R. and E_(1/10) of theelectrophotographic material can be furthermore improved.

In the general formula (Ia), T₁ and T₂ each preferably represents ahydrogen atom, a chlorine atom, a bromine atom, and as a hydrocarbongroup having from 1 to 10 carbon atoms, an alkyl group having from 1 to4 carbon atoms (e.g., methyl, ethyl, propyl, and butyl), an aralkylgroup having from 7 to 9 carbon atoms (e.g., benzyl, phenethyl,3-phenylpropyl, chlorobenzyl, dichlorobenzyl, bromobenzyl, methylbenzyl,methoxybenzyl, and chloromethylbenzyl), an aryl group (e.g., phenyl,tolyt, xylyl, bromophenyl, methoxyphenyl, chlorophenyl, anddichlorophenyl), --COR_(a) or --COOR_(a) (wherein R_(a) preferablyrepresents any of the above-recited hydrocarbon groups described aspreferred hydrocarbon groups having from 1 to 10 carbon atoms).

In the general formulae (Ia) and (Ib), L₁ and L₂ each represents a merebond or a linking group containing from 1 to 4 linking atoms whichconnects between --COO-- and the benzene ring, e.g., --CH₂)_(n1)(wherein n₁ represents an integer of from 1 to 3), --CH₂ OCO--, --CH₂CH₂ OCO--, --CH₂)_(m1) (wherein m₁ represents an integer of 1 or 2), and--CH₂ CH₂ O--, and preferably represents a mere bond or a linking groupcontaining from 1 to 2 linking atoms.

Specific examples of the polymer component corresponding to therepeating unit represented by the general formula (Ia) or (Ib) which canbe used in the resin (A) according to the present invention are setforth below, but the present invention should not be construed as beinglimited thereto. In the following formulae (a-1) to (a-17), n representsan integer of from 1 to 4; m represents an integer of from 0 to 3; prepresents an integer of from 1 to 3; R₁₀ to R₁₃ each represents --C_(n)H_(2n+1) or --(CH₂)_(m) C₆ H₅ (wherein n and m each has the same meaningas defined above); and X₁ and X₂, which may be the same or different,each represents a hydrogen atom, --Cl, --Br or --I. ##STR5##

Now, the polymer component having the specified polar group present inthe resin (A) will be described in detail below.

The polymer component having the specified polar group can exist eitherin the polymer chain of the resin (A), at one terminal of the polymerchain or both of them.

The polar group included in the polar group-containing polymer componentis selected from --PO₃ H₂, --SO₃ H, --COOH, ##STR6## and a cyclic acidanhydride-containing group, as described above.

In the group ##STR7## above, R¹ represents a hydrocarbon group or --OR²(wherein R² represents a hydrocarbon group). The hydrocarbon grouprepresented by R¹ or R² preferably includes an aliphatic group havingfrom 1 to 22 carbon atoms which may be substituted (e.g., methyl, ethyl,propyl, butyl, hexyl, octyl, decyl, dodecyl, octadecyl, 2-chloroethyl,2-methoxyethyl, 3-ethoxypropyl, allyl, crotonyl, butenyl, cyclohexyl,benzyl, phenethyl, 3-phenylpropyl, methylbenzyl, chlorobenzyl,fluorobenzyl, and methoxybenzyl) and an aryl group which may besubstituted (e.g., phenyl, tolyl, ethylphenyl, propylphenyl,chlorophenyl, fluorophenyl, bromophenyl, chloromethylphenyl,dichlorophenyl, methoxyphenyl, cyanophenyl, acetamidophenyl,acetylphenyl, and butoxyphenyl).

The cyclic acid anhydride-containing group is a group containing atleast one cyclic acid anhydride. The cyclic acid anhydride to becontained includes an aliphatic dicarboxylic acid anhydride and anaromatic dicarboxylic acid anhydride.

Specific examples of the aliphatic dicarboxylic acid anhydrides includesuccinic anhydride ring, glutaconic anhydride ring, maleic anhydridering cyclopentane-1,2-dicarboxylic acid anhydride ringcyclohexane-1,2-dicarboxylic acid anhydride ringcyclohexene-1,2-dicarboxylic acid anhydride ring, and2,3-bi-cyclo[2,2,2]octanedicarboxylic acid anhydride. These rings may besubstituted with, for example, a halogen atom such as a chlorine atomand a bromine atom, and an alkyl group such as a methyl group, an ethylgroup, a butyl group and a hexyl group.

Specific examples of the aromatic dicarboxylic acid anhydrides includephthalic anhydride ring, naphthalenedicarboxylic acid anhydride ring,pyridinedicarboxylic acid anhydride ring and thiophenedicarboxylic acidanhydride ring. These rings may be substituted with, for example, ahalogen atom (e.g., chlorine and bromine), an alkyl group (e.g., methyl,ethyl, propyl, and butyl), a hydroxyl group, a cyano group, a nitrogroup, and an alkoxycarbonyl group (e.g., methoxy and ethoxy as thealkoxy group).

In a case wherein the polar group is present in the polymer chain of theresin (A), the polar group may be bonded to the polymer main chaineither directly or via an appropriate linking group. The linking groupcan be any group for connecting the polar group to the polymer mainchain. Specific examples of suitable linking group include ##STR8##(wherein d₁ and d₂, which may be the same or different, each representsa hydrogen atom, a halogen atom (e.g., chlorine, and bromine), ahydroxyl group, a cyano group, an alkyl group (e.g., methyl, ethyl,2-chloroethyl, 2-hydroxyethyl, propyl, butyl, and hexyl), an aralkylgroup (e.g., benzyl, and phenethyl), or a phenyl group), ##STR9##(wherein d₃ and d₄ each has the same meaning as defined for d₁ or d₂above), --C₆ H₁₀, --C₆ H₄ --, --O--, --S--, ##STR10## (wherein d₅represents a hydrogen atom or a hydrocarbon group (preferably havingfrom 1 to 12 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl,octyl, decyl, dodecyl, 2-methoxyethyl, 2-chloroethyl, 2-cyanoethyl,benzyl, methylbenzyl, phenethyl, phenyl, tolyl, chlorophenyl,methoxyphenyl, and butylphenyl)), --CO--, --COO--, --OCO--, --CON(d₅)--,--SO₂ N(d₅)--, --SO₂ --, --NHCONH--, --NHCOO--, --NHSO₂ --, --CONHCOO--,--CONHCONH--, a heterocyclic ring (preferably a 5-membered or 6-memberedring containing at least one of an oxygen atom, a sulfur atom and anitrogen atom as a hetero atom or a condensed ring thereof (e.g.,thiophene, pyridine, furan, imidazole, piperidine, and morpholinerings)), ##STR11## (wherein d₆ and d7 which may be the same ordifferent, each represents a hydrocarbon group or --Od₈ (wherein d₈represents a hydrocarbon group)), and a combination thereof. Suitableexamples of the hydrocarbon groups include those described for d₅.

The polymer component containing the polar group may be any of specifiedpolar group-containing vinyl compounds copolymerizable with, forexample, monomer corresponding to the repeating unit represented by thegeneral formula (I) (including that represented by the general formula(Ia) or (Ib)) . Examples of such vinyl compounds are described, e.g., inKobunshi Gakkai (ed.), Kobunshi Data Handbook Kisohen (Polymer DateHandbook Basis), Baifukan (1986). Specific examples of these vinylmonomers include acrylic acid, α- and/or β-substituted acrylic acids(e.g., α-acetoxy, α-acetoxymethyl, α-(2-amino)-ethyl, α-chloro, α-bromo,α-fluoro, α-tributylsilyl, α-cyano, β-chloro, β-bromo,α-chloro-β-methoxy, and α,β-dichloro compounds), methacrylic acid,itaconic acid, itaconic half esters, itaconic half amides, crotonicacid, 2-alkenylcarboxylic acids (e.g., 2-pentenoic acid,2-methyl-2-hexenoic acid, 2-octenoic acid, 4-methyl-2-hexenoic acid, and4-ethyl-2-octenoic acid), maleic acid, maleic half esters, maleic halfamides, vinylbenzenecarboxylic acid, vinylbenzenesulfonic acid,vinylsulfonic acid, vinylphosphonic acid, dicarboxylic acid vinyl orallyl half esters, and ester or amide derivatives of these carboxylicacids or sulfonic acids containing the specific polar group in thesubstituent thereof.

Specific examples of the polar group-containing polymer components areset forth below, but the present invention should not be construed asbeing limited thereto. In the following formulae, e₁ represents --H or--CH₃ ; e₂ represents --H, --CH₃ or --CH₂ COOCH₃ ; R₁₄ represents analkyl group having from 1 to 4 carbon atoms; R₁₅ represents an alkylgroup having from 1 to 6 carbon atoms, a benzyl group or a phenyl group;c represents an integer of from 1 to 3; d represents an integer of from2 to 11; e represents an integer of from 1 to 11; f represents aninteger of from 2 to 4; and g represents an integer of from 2 to 10.##STR12##

In such a case, the polar group is included in a component (repeatingunit) for forming the polymer chain of the resin (A) and the polargroups can be present in the resin (A) regularly (in a case of a blockpolymer) or irregularly (in case of a random polymer).

In a case wherein the polar group is present at one terminal of thepolymer chain of the resin (A), the polar group may be bonded to theterminal of the polymer main chain either directly or via an appropriatelinking group. Suitable examples of the linking groups include thoseillustrated for the cases wherein the polar groups are present in thepolymer chain hereinbefore described.

When the polar group is present at one terminal of polymer main chain ofthe resin (A) as described above, other polar groups are not necessaryto exist in the polymer chain. However, the resin (A) having thespecified polar groups in the polymer chain in addition to the polargroup bonded to the terminal of the main chain is preferable since theelectrostatic characteristics are further improved. The polar groupspresent may be the same or different.

In the resin (A), the ratio of the polar group present in the polymerchain to the polar group bonded to the terminal of the polymer mainchain may be varied depending on the kinds and amounts of other binderresins, a spectral sensitizing dye, a-chemical sensitizer and otheradditives which constitute the photoconductive layer according to thepresent invention, and can be appropriately controlled. What isimportant is that the total amount of the polar group-containingcomponent present in the resin (A) is from 0.5 to 15% by weight.

The resin (A) (including resin (A')) according to the present inventionmay further comprise repeating units corresponding to othercopolymerizable monomers as polymer components in addition to therepeating unit of the general formula (I), (Ia) and/or (Ib) and therepeating unit containing the polar group optionally present.

Examples of such monomers include, in addition to methacrylic acidesters, acrylic acid esters and crotonic acid esters containingsubstituents other than those described for the general formula (I),α-olefins, vinyl or allyl esters of carboxylic acids (including, e.g.,acetic acid, propionic acid, butyric acid, valetic acid, benzoic acid,-and naphthalenecarboxylic acid, as examples of the carboxylic acids),acrylonitrile, methacrylonitrile, vinyl ethers, iraconic acid esters(e.g., dimethyl ester and diethyl ester), acrylamides, methacrylamides,styrenes (e.g., styrene, vinyltoluene, chlorostyrene, hydroxystyrene,N,N-dimethylaminomethylstyrene, methoxycarbonylstyrene,methanesulfonyloxystyrene, and vinylnaphthalene),vinylsulfone-containing compounds, vinylketone-containing compounds, andheterocyclic vinyl compounds (e.g., vinylpyrrolidone, vinylpyridine,vinylimidazole, vinylthiophene, vinylimidazoline, vinylpyrazoles,vinyldioxane, vinylquinoline, vinyltetrazole, and vinyloxazine). It ispreferred that the content of the polymer components corresponding tosuch other monomers does not exceed 30% by weight of the resin (A).

The resin (A) having the specified polar groups at random in the polymerchain thereof can be easily synthesized according to a conventionallyknown method, for example, a radical polymerization method or an ionpolymerization method using a monomer corresponding to the repeatingunit represented by the general formula (I), a monomer corresponding tothe repeating unit containing the specified polar group and, if desired,other monomers by appropriately selecting the polymerization conditionso as to obtain the resin having the desired molecular weight. A radicalpolymerization method is preferred because purification of the monomersand solvent to be used is unnecessary and a very low polymerizationtemperature such as 0° C. or below is not required. Specifically, apolymerization initiator used includes an azobis type initiator and aperoxide compound each of which is conventionally known. In order tosynthesize the resin having the low molecular weight according to thepresent invention, a known method, for example, increase in the amountof initiator used or regulation of a high polymerization temperature maybe utilized. In general, the amount of initiator used is in a range offrom 0.1 to 20 parts by weight based on the total amount of the monomersemployed, and the polymerization temperature is regulated in a range offrom 30° C. to 200° C. Moreover, a method using a chain transfer agenttogether may be employed. Specifically, a chain transfer agent, forexample, a mercapto compound, or a halogenated compound is used in arange of from 0.01 to 10 parts by weight based on the total amount ofthe monomers employed to adjust the desired weight average molecularweight.

The resin (A) having the specified polar groups as a block in thepolymer chain thereof used in the present invention can be produced by aconventionally known polymerization reaction method. More specifically,it can be produced according to a method for producing the AB blockcopolymer described hereinafter with respect to the resin (B).

The resin (A) according to the present invention, in which the specificpolar group is bonded to only one terminal of the polymer main chain,can easily be prepared by an ion polymerization process, in which avarious kind of reagents is reacted at the terminal of a living polymerobtained by conventionally known anion polymerization or cationpolymerization; a radical polymerization process, in which radicalpolymerization is performed in the presence of a polymerizationinitiator and/or a chain transfer agent which contains the specificpolar group in the molecule thereof; or a process, in which a polymerhaving a reactive group (for example, an amino group, a halogen atom, anepoxy group, and an acid halide group) at the terminal obtained by theabove-described ion polymerization or radical polymerization issubjected to a polymer reaction to convert the terminal reactive groupinto the specific polar group.

More specifically, reference can be made to, e.g., P. Dreyfuss and R. P.Quirk, Encycl. Polym. Sci. Eng., 7, 551 (1987), Yoshiki Nakajo and YuyaYamashita, Senryo to Yakuhin (Dyes and Chemicals)., 30, 232 (1985),Akira Ueda and Susumu Nagai, Kagaku to Koqyo (Science and Industry), 60,57 (1986) and literature references cited therein.

Specific examples of chain transfer agents which can be used includemercapto compounds containing the polar group or the reactive groupcapable of being converted into the polar group (e.g., thioglycolicacid, thiomalic acid, thiosalicylic acid, 2-mercaptopropionic acid,3-mercaptopropionic acid, 3-mercaptobutyric acid,N-(2-mercaptopropionyl)glycine, 2-mercaptonicotinic acid,3-[N-(2-mercaptoethyl)carbamoyl]propionic acid,3-[N-(2-mercaptoethyl)amino]propionic acid,N-(3-mercaptopropionyl)alanine, 2-mercaptoethanesulfonic acid,3-mercaptopropanesulfonic acid, 4-mecaptobutanesulfonic acid,2-mercaptoethanol, 3-mercapto-1,2-propanediol, 1-mercapto-2-propanol,3-mercapto-2-butanol, mercaptophenol, 2-mercaptoethylamine,2-mercaptoimidazole, 2-mercapto-3-pyridinol, 4-(2-mercaptoethyloxycarbonyl)-phthalic acid anhydride,2-mercaptoethylphosphonic acid anhydride, and monomethyl2-mercaptoethylphosphonate), and alkyl iodide compounds containing thepolar group or the polar group-forming reactive group (e.g., iodoaceticacid, iodopropionic acid, 2-iodoethanol, 2-iodoethanesulfonic acid, and3-iodopropanesulfonic acid).

Specific examples of the polymerization initiators containing the polargroup or the reactive group include 4,4'-azobis(4-cyanovaleric acid),4,4'-azobis(4-cyanovaleric acid chloride), 2,2'-azobis(2-cyanopropanol),2,2'-azobis(2-cyanopentanol),2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide),2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]-propane),2,2'-azobis[2-(2-imidazolin-2-yl)propane], and2,2'-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane].

The chain transfer agent or polymerization initiator is usually used inan amount of from 0.5 to 15 parts by weight, preferably from 2 to 10parts by weight, per 100 parts by weight of the total monomers used.

Further, the resin (A) having the specific polar group at the terminalof the polymer main chain can be produced by a photopolymerizationmethod using a dithiocarbamate group-containing compound or xanthategroup-containing compound containing as a substituent the specific polargroup, as a photo-initiator. Specifically, it can be easily preparedaccording to a method described in the references cited for theproduction of the resin (B) hereinafter.

Examples of the dithiocarbamate group or xanthate group containingcompound include those represented by the general formula (PI) or (PII)described below. ##STR13## wherein R²³, R²⁴, R²⁵, R²⁶ and R²⁷ eachrepresents a hydrocarbon group and at least one of R²³ R²⁴ and R²⁵ or atleast one of R²⁶ and R²⁷ contains at least one of the above describedspecific polar groups as a substituent. Specific examples of thehydrocarbon group include those described for R³ in the general formula(I) described above.

Now, the resin (B) which can be used as the binder resin for thephotoconductive layer of the electrophotographic light-sensitivematerial according to the present invention will be described in moredetail below.

The resin (B) is an AB block copolymer comprising an A block whichcomprises a polymer component containing the specific polar group and aB block which comprises a polymer component corresponding to therepeating unit represented by the general formula (I) and does notcontain a polymer component containing the specific polar groupdescribed above.

The AB block copolymer according to the present invention includes ablock copolymer wherein the A block and the B block are bonded eachother (Embodiment (1)), a block copolymer of Embodiment (1) wherein thespecific polar group is bonded at one terminal of the A block polymerchain and the B block is bonded at the other terminal of the A blockpolymer chain (Embodiment (2)), and a block copolymer wherein the Bblocks are bonded at both terminals of the A block polymer chain(Embodiment (3)). These AB block copolymers are schematicallyillustrated as follows.

    ______________________________________                                        Embodiment (1)                                                                             (A Block)-b-(B Block)                                            Embodiment (2)                                                                             (Polar Group)-(A Block)-b-(B Block)                              Embodiment (3)                                                                             (B Block)-b-(A Block)-b-(B Block)                                ______________________________________                                    

wherein --b-- represents a bond connecting two blocks present on bothsides.

The resin (B) is characterized by containing from 0.05 to 10% by weightof polymer component containing the specific polar group and not lessthan 30% by weight of polymer component represented by the generalformula (I) based on the resin (B) as described above.

If the content of the polar group-containing component in the resin (B)is less than 0.05% by weight, the initial potential is low and thussatisfactory image density can not be obtained. On the other hand, ifthe content of the polar group-containing component is larger than 10%by weight, various undesirable problems may occur, for example, thedispersibility is reduced, the film smoothness and theelectrophotographic characteristics under high temperature and highhumidity condition are reduced, and further when the light-sensitivematerial is used as an offset master plate, the occurrence of backgroundstains increases.

It is also preferred that the total amount of the specific polargroup-containing polymer component contained in the resin (B) is from 10to 50% by weight based on the total amount of the specific polargroup-containing polymer component present in the resin (A).

If the total amount of the specific polar group-containing component inthe resin (B) is less than 10% by weight of that in the resin (A), theelectrophotographic characteristics (particularly, dark decay retentionrate and photosensitivity) and film strength tend to decrease. On theother hand, if it is larger than 50% by weight, a sufficiently uniformdispersion may not be obtained, thereby the electrophotographiccharacteristics decrease and water retentivity decline when used as anoffset master plate.

The weight average molecular weight of the resin (B) is from 3×10⁴ to1×10⁶, and preferably from 5×10⁴ to 5×10⁵. If the weight averagemolecular weight of the resin (B) is less than 3×10⁴, the film-formingproperty of the resin is lowered, thereby a sufficient film strengthcannot be maintained, while if the weight average molecular weight ofthe resin (B) is higher than 1×10⁶, the effect of the resin (B) of thepresent invention is reduced, whereby the electrophotographiccharacteristics thereof become almost the same as those ofconventionally known resins.

The glass transition point of the resin (B) is preferably from -10° C.to 100° C., and more preferably from 0° C. to 90° C.

Specific examples of the polymer component containing the specific polargroup which constitutes the A block of the AB block copolymer (resin(B)) according to the present invention include those for the polymercomponent containing the specific polar group present in the resin (A)described above.

Two or more kinds of the polymer components containing the specificpolar group may be employed in the A block. In such a case, two or morekinds of the polar group-containing components may be contained in the Ablock in the form of a random copolymer or a block copolymer.

The A block may contain other polymer components than the polargroup-containing polymer components. Preferred examples of such otherpolymer components include those corresponding to the repeating unitrepresented by the following general formula (II): ##STR14## wherein D¹represents --COO--, --OCO--, --CH₂)_(k) OCO--, --CH₂)_(k) COO--, --O--,--SO₂ --, --CO--, ##STR15## --CONHCOO--, --CONHCONH-- or (wherein krepresents an integer of from 1 to 3; and D³ represents a hydrogen atomor a hydrocarbon group); D² represents a hydrocarbon group; and m¹ andm² which may be the same or different, each has the same meaning as a¹or a² in the general formula (I).

Preferred examples of the hydrocarbon group represented by D³ include analkyl group having from 1 to 18 carbon atoms which may be substituted(e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,decyl, dodecyl, hexadecyl, octadecyl, 2-chloroethyl, 2-bromoethyl,2-cyanoethyl, 2-methoxycarbonylethyl, 2-methoxyethyl, and3-bromopropyl), an alkenyl group having from 4 to 18 carbon atoms whichmay be substituted (e.g., 2-methyl-l-propenyl, 2-butenyl, 2-pentenyl,3-methyl,2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, and4-methyl-2-hexenyl), an aralkyl group having from 7 to 12 carbon atomswhich may be substituted (e.g., benzyl, phenethyl, 3-phenylpropyl,naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl,methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, anddimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclohexyl, 2-cyclohexylethyl, and2-cyclopentylethyl), and an aromatic group having from 6 to 12 carbonatoms which may be substituted (e.g., phenyl, naphthyl, tolyl, xylyl,propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl,ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl,dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, butoxycarbonylphenyl,acetamidophenyl, propioamidophenyl, and dodecyloylamidophenyl) .

When D¹ represents ##STR16## the benzene ring may be substituted.Suitable examples of the substituents include a halogen atom (e.g.,chlorine, and bromine), an alkyl group (e.g., methyl, ethyl, propyl,butyl, chloromethyl, and methoxymethyl), and an alkoxy group (e. g.,methoxy, ethoxy, propoxy, and butoxy).

Preferred examples of the hydrocarbon group represented by D² include analkyl group having from 1 to 22 carbon atoms which may be substituted(e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl,2-chloroethyl, 2-bromoethyl, 2-cyanoethyl, 2-methoxycarbonylethyl,2-methoxyethyl, and 3-bromopropyl), an alkenyl group having from 4 to 18carbon atoms which may be substituted (e.g., 2-methyl-1-propenyl,2-butenyl, 2-pentenyl, 3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl,2-hexenyl, and 4-methyl-2-hexenyl), an aralkyl group having from 7 to 12carbon atoms which may be substituted (e.g., benzyl, phenethyl,3-phenylpropyl, naphthylmethyl, 2-naphthylethyl, chlorobenzyl,bromobenzyl, methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl,and dimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclohexyl, 2-cyclohexylethyl, and2-cyclopentylethyl), and an aromatic group having from 6 to 12 carbonatoms which may be substituted (e.g., phenyl, naphthyl, tolyl, xylyl,propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl,ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl,dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, butoxycarbonylphenyl,acetamidophenyl, propioamidophenyl, and dodecyloylamidophenyl).

More preferably, in the general formula (II), D¹ represents --COO--,--OCO--, --CH₂ OCO--, --CH₂ COO--, --O--, --CONH--, --SO₂ NH-- or##STR17##

Moreover, the A block may further contain other polymer componentscorresponding to mohomers copolymerizable with monomers corresponding tothe polymer components represented by the general formula (II). Examplesof such monomers include acrylonitrile, methacrylonitrile, andheterocyclic vinyl compounds (e.g., vinylpyridine, vinylimidazole,vinylpyrrolidone, vinylthiophene, vinylpyrazole, vinyldioxane, andvinyloxazine). However, such other monomers are preferably employed inan amount of not more than 20 parts by weight per 100 parts by weight ofthe total polymer components constituting the A block.

The polymer component which constitutes the B block of the AB blockcopolymer (resin (B)) will be described in greater detail below.

The B block contains at least the polymer component corresponding to therepeating unit represented by the general formula (I) described above.The content of the polymer component corresponding to the generalformula (I) in the B block is preferably not less than 30% by weight,more preferably not less than 50% by weight.

The polymer component corresponding to the general formula (I) is thesame as that described in detail with respect to the resin (A)hereinbefore. As other polymer components, the B block may contain theabove described polymer components represented by the general formula(II) and above described other polymer components corresponding tomonomers copolymerizable with monomers corresponding to the polymercomponents represented by the general formula (II) which may be presentin the A block described above. However, the B block does not containany specified polar group-containing polymer component used in the Ablock.

Preferred examples of polymer components constituting the B blockinclude those represented by the general formula (I) wherein both a¹ anda² are hydrogen atoms and the hydrocarbon group represented by R³ is analkyl group having from 1 to 6 carbon atoms which may be substituted(e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-chloroethyl,2-cyanoethyl, 2-methoxyethyl, 2-thienylethyl, and 2,3-dichloropropyl),and those represented by the general formula (II) wherein both m¹ and m²are hydrogen atoms and the hydrocarbon group represented by D² isselected from the alkyl group described for R³ above.

The AB block copolymer (resin (B)) used in the present invention can beproduced by a conventionally known polymerization reaction method. Morespecifically, it can be produced by the method comprising previouslyprotecting the specific polar group of a monomer corresponding to thepolymer component having the specific polar group to form a functionalgroup, synthesizing an AB block copolymer by a so-called known livingpolymerization reaction, for example, an ion polymerization reactionwith an organic metal compound (e.g., alkyl lithiums, lithiumdiisopropylamide, and alkyl-magnesium halides) or a hydrogeniodide/iodine system, a photopolymerization reaction using a porphyrinmetal complex as a catalyst, or a group transfer polymerizationreaction, and then conducting a protection-removing reaction of thefunctional group which had been formed by protecting the polar group bya hydrolysis reaction, a hydrogenolysis reaction, an oxidativedecomposition reaction, or a photodecomposition reaction to form thepolar group. One example thereof is .shown by the following reactionscheme (1): ##STR18##

Specifically, the AB block copolymer can be easily synthesized accordingto the synthesis methods described, e.g., in P. Lutz, P. Masson et al,Polym. Bull., 12, 79 (1984), B. C. Anderson, G. D. Andrews et al,Macromolecules, 14, 1601 (1981), K. Hatada, K. Ute et al, Polym. J., 17,977 (1985), ibid., 18, 1037 (1986), Koichi Ute and Koichi Hatada,Kobunshi Kako (Polymer Processing), 36, 366 (1987), ToshinobuHigashimura and Mitsuo Sawamoto, Kobunshi Ronbun Shu (Polymer Treatises,46, 189 (1989), M. Kuroki and T. Aida, J. Am. Chem. Soc., 109, 4737(1989), Teizo Aida and Shohei Inoue, Yuki Gosei Kagaku (OrganicSynthesis Chemistry), 43, 300 (1985), and D. Y. Sogah, W. R. Hertler etal, Macromolecules, 20, 1473 (1987).

Also, the protection of the specific polar group by a protective groupand the release of the protective group (a reaction for removing aprotective group) can be easily conducted by utilizing conventionallyknown knowledges. More specifically, they can be performed byappropriately selecting methods described, e.g., in Yoshio Iwakura andKeisuke Kurita, Hannosei Kobunshi (Reactive Polymer), Kodansha (1977),T. W. Greene, Protective Groups in Orqanic Synthesis, John Wiley & Sons(1981), and J. F. W. McOmie, Protective Groups in Organic Chemistry,Plenum Press, (1973), as well as the methods as described in the abovereferences.

Further, the AB block copolymer can be also synthesized by performing apolymerization reaction under light irradiation using a monomer havingan unprotected polar group and also using a dithiocarbamategroup-containing compound and/or xanthate group-containing compound asan initiator. For example, the block copolymer can be synthesizedaccording to the synthesis methods described, e.g., in Takayuki Otsu,Kobunshi (Polymer), 37, 248 (1988), Shunichi Himori and Ryuichi Otsu,Polym. Rep. Jap. 37, 3508 (1988), JP-A-64-111, JP-A-64-26619, NobuyukiHigashi et al, Polymer Preprints Japan, 36, (6), 1511 (1987), and M.Niwa, N. Higashi et al, J. Macromol. Sci. Chem., A24, (5), 567 (1987).

Moreover, the AB block copolymer can be synthesized by a method whereinan azobis compound containing either the A block portion or the B blockportion is synthesized and using the resulting polymer azobis initiatoras an initiator, a radical polymerization reaction is conducted withmonomers for forming another block. Specifically, the AB block copolymercan be synthesized by the methods described, for example, in Akira Uedaand Susumu Nagai, Kobunshi Ronbun Shu, 44, 469(1987), and Akira Ueda,Osakashiritsu Kogyo Kenkyusho Hokoku, 84, (1989).

In case of utilizing the above described synthesis method, a weightaverage molecular weight of the polymer azobis initiator is preferablynot more than 2×10⁴ in view of the easy synthesis of polymer azobisinitiator and the regular polymerization reaction for the formation ofblock. On the other hand, it is preferred that the polymer chain of Bblock is longer than that of A block in the resin (B) according to thepresent invention. As a result, a polymer azobis initiator containingthe A block portion is preferably employed when the AB block copolymeris synthesized according to the method. For example, the AB blockcopolymer is synthesized according to the following reaction scheme (2):##STR19##

The resin (B) can have the specific polar group bonded either directlyor via an appropriate linking group to one terminal of the polymer chainof the A block comprising the polar group-containing polymer componentas described above. In such a case, the polar group bonded to theterminal may be the same as or different from the polar group present inthe polymer component constituting the A block. Suitable examples of thelinking groups include those illustrated for the cases wherein the polargroups are present in the polymer chain of the resin (A) describedhereinbefore.

The AB block copolymer having the specific polar group at the terminalof its polymer chain can be produced by a conventionally knownpolymerization reaction method. More specifically, it can be produced bya method comprising previously protecting the specific polar group of amonomer corresponding to the polymer component having the specific polargroup to form a functional group, synthesizing an AB block copolymer bya so-called known living polymerization reaction, for example, an ionpolymerization reaction with an organic metal compound (e.g., alkyllithiums, lithium diisopropylamide, and alkylmagnesium halides) or ahydrogen iodide/iodine system, a photopolymerization reaction using aporphyrin metal complex as a catalyst, or a group transferpolymerization reaction, introducing directly the specific polar groupor introducing at first a functional group capable of connecting thespecific polar group, then chemically bonding the specific polar group,at the stop reaction, and then conducting a protection-removing reactionof the functional group formed by protecting the polar group in thepolymer by a hydrolysis reaction, hydrogenolysis reaction, an oxidativedecomposition reaction, or a photodecomposition reaction to form thepolar group. One of the examples is shown by the following reactionscheme (3): ##STR20##

Specifically, the AB block copolymer can be easily synthesized accordingto the synthesis methods described, e.g., in P. Lutz, P. Masson et al,Polym. Bull., 12, 79 (1984), B. C. Anderson, G. D. Andrews et al,Macromolecules, 14, 1601 (1981), K. Hatada, K. Ute et al, Polym. J., 17,977 (1985), ibid., 18, 1037 (1986), Koichi Ute and Koichi Hatada,Kobunshi Kako (Polymer Processing), 36, 366 (1987), ToshinobuHigashimura and Mitsuo Sawamoto, Kobunshi Ronbun Shu (Polymer Treaties),46, 189 (1987), M. Kuroki and T. Aida, J. Am. Chem. Soc., 109, 4737(1989 ), Teizo Aida and Shohei Inoue, Yuki Gosei Kagaku (OrganicSynthesis Chemistry), 43, 300 (1985), and D. Y. Sogah, W. R. Hertler etal, Macromolecules, 20, 1473 (1987).

Furthermore, the AB block copolymer can also be synthesized byperforming a polymerization reaction under light irradiating using amonomer having an unprotected polar group and also using adithiocarbamate group-containing compound and/or xanthategroup-containing compound which also contains the specific polar groupas a substituent as an initiator. For example, the block copolymer canbe synthesized according to the synthesis methods described in TakayukiOtsu, Kobunshi (Polymer), 37, 248 (1988), Shunichi Himori and RyuichiOhtsu, Polym. Rep. Jap. 37, 3508 (1988), JP-A-64-111, JP-A-64-26619,Nobuyuki Higashi et al, Polymer Preprints Japan, 36, (6), 1511 (1987),and M. Niwa, N. Higashi et al, J. Macromol. Sci. Chem., A24, (5), 567(1987).

Also, the protection of the specific polar group by a protective groupand the release of the protective group (a reaction for removing aprotective group) described above can be easily conducted by utilizingconventionally known knowledges. More specifically, they can beperformed by appropriately selecting methods described, e.g., in YoshioIwakura and Keisuke Kurita, Hannosei Kobunshi (Reactive polymer),Kodansha (1977), T.W. Greene, Protective Groups in Orqanic Synthesis,John Wiley & Sons (1981), and J.F.W. McOmie, Protective Groups inOrqanic Chemistry, Plenum Press, (1973), as well as the methods asdescribed in the above references.

Of the resin (B), the block copolymer wherein the B blocks are bonded tothe both terminals of the A block (hereinafter sometimes referred to asa BAB block copolymer) is described below.

The B blocks bonded to the both terminals of the A block may bestructurally the same or different and each contains the polymercomponent represented by the general formula (I) and does not containthe specific polar group-containing component present in the A block.The lengths of the polymer chains may be the same or different.

The BAB block copolymer used in the present invention can be produced bya conventionally known polymerization reaction method. Morespecifically, it can be produced by the method comprising previouslyprotecting the specific polar group of a monomer corresponding to thepolymer component having the specific polar group to form a functionalgroup, synthesizing an AB block copolymer by a so-called known livingpolymerization reaction, for example, an ion polymerization reactionwith an organic metal compound (e.g., alkyl lithiums, lithiumdiisopropylamide, and alkylmagnesium halides) or a hydrogeniodide/iodine system, a photopolymerization reaction using a porphyrinmetal complex as a catalyst, or a group transfer polgmerizationreaction, and then conducting a protection-removing reaction of thefunctional group which had been formed by protecting the polar.group bya hydrolysis reaction, a hydrogenolysis reaction, an oxidativedecomposition reaction, or a photodecomposition reaction to form thepolar group. One example thereof is shown by the following reactionscheme (4): ##STR21##

Specifically, the BAB block copolymer can be easily synthesizedaccording to the synthesis methods described, e.g., in P. Lutz, P.Masson et al, Polym. Bull., 12, 79 (1984), B. C. Anderson, G. D. Andrewset al, Macromolecules, 14, 1601 (1981), K. Hatada, K. Ute et al, Polym.J., 17, 977 (1985), ibid., 18, 1037 (1986), Koichi Ute and KoichiHatada, Kobunshi Kako (Polymer Processing), 36, 366 (1987), ToshinobuHigashimura and Mitsuo Sawamoto, Kobunshi Ronbun Shu (Polymer Treatises,46, 189 (1989), M. Kuroki and T. Aida, J. Am. Chem. Soc., 109, 4737(1989), Teizo Aida and Shohei Inoue, Yuki Gosei Kagaku (OrganicSynthesis Chemistry), 43, 300 (1985), and D. Y. Sogah, W. R. Hertler etal, Macromoleculeg, 20, 1473 (1987), M. Morton, T. E. Helminiake et al,J. Polym. Sci., 57, 471 (1962), B. Gordon III, M. Blumenthal and J. E.Loftus, Polym. Bull., 11, 349 (1984), and R. B. Bates, W. A. Beavers etal, J. Org. Chem., 44, 3800 (1979).

Also, the protection of the specific polar group by a protective groupand the release of the protective group (a reaction for removing aprotective group) can be easily conducted by utilizing conventionallyknown knowledges. More specifically, they can be performed byappropriately selecting methods described, e.g., in Yoshio Iwakura andKeisuke Kurita, Hannosei Kobunshi (Reactive Polymer), Kodansha (1977),T. W. Greene, Protective Groups in Orqanic Synthesis, John Wiley & Sons(1981), and J. F. W. McOmie, Protective Groups in Organic Chemistry,Plenum Press, (1973), as well as the methods as described in the abovereferences.

Further, the BAB block copolymer can also be synthesized by performing apolymerization reaction under light irradiation using a monomer havingan unprotected polar group and also using a dithiocarbamategroup-containing compound and/or a xanthate group-containing compound asan initiator. For example, the block copolymer can be synthesizedaccording to the synthesis methods described, e.g., in Takayuki Otsu,Kobunshi (Polymer), 37, 248 (1988), Shunichi Himori and Ryuichi Otsu,Polym. Rep. Jap. 37, 3508 (1988), JP-A-64-111, JP-A-64-26619, NobuyukiHigashi et al, Polymer Preprints Japan, 36, (6), 1511 (1987), and M.Niwa, N. Higashi et al, J. Macromol. Sci. Chem., A24, (5), 567 (1987).

The ratio of resin (A) to resin (B) used in the present invention ispreferably 0.05 to 0.60/0.95 to 0.40, more preferably 0.10 to 0.40/0.90to 0.60 by means of a weight ratio of resin (A)/resin (B).

When the weight ratio of resin (A)/resin (B) is less than 0.05, theeffect for improving the electrostatic characteristics may be reduced.On the other hand, when it is more than 0.60, the film strength of thephotoconductive layer may not be sufficiently maintained in some cases(particularly, in case of using as an electrophotographic printing plateprecursor).

Furthermore, in the present invention, the binder resin used in thephotoconductive layer may contain other resin(s) known for inorganicphotoconductive substance in addition to the resin (A) and resin (B)according to the present invention. However, the amount of other resinsdescried above should not exceed 30% parts by weight per 100 parts byweight of the total binder resins since, if the amount is more than 30parts by weight, the effects of the present invention are remarkablyreduced.

Representative other resins which can be employed together with theresins (A) and (B) according to the present invention include vinylchloride-vinyl acetate copolymers, styrene-butadiene copolymers,styrene-methacrylate copolymers, methacrylate copolymers, acrylatecopolymers, vinyl acetate copolymers, polyvinyl butyral resins, alkydresins, silicone resins, epoxy resins, epoxyester resins, and polyesterresins.

Specific examples of other resins used are described, for example, inTakaharu Shibata and Jiro Ishiwatari, Kobunshi (High MolecularMaterials), 17, 278 (1968), Harumi Miyamoto and Hidehiko Takei, ImagingNo. 8, 9 (1973), Koichi Nakamura, Kiroku Zairyoyo Binder no JissaiGijutsu (Practical Technique of Binders for Recording Materials), Cp.10, published by C. M. C. Shuppan (1985), D. Tatt, S. C. HeideckerTappi, 49, No. 10, 439 (1966), E. S. Baltazzi, R. G. Blanckette, et al.,Photo Sci Eng., 16, No 5, 354 (1972), Nguyen Chank Keh, Isamu Shimizuand Eiichi Inoue, Denshi Shashin Gakkaishi (Journal ofElectrophotoqraphic Association), 18, No. 2, 22 (1980), JP-B-50-31011,JP-A-53-54027, JP-A-54-20735, JP-A-57-202544 and JP-A-58-68046.

The total amount of binder resin used in the photoconductive layeraccording to the present invention is preferably from 10 to 100 parts byweight, more preferably from 15 to 50 parts by weight, per 100 parts byweight of the inorganic photoconductive substance.

When the total amount of binder resin used is less than 10 parts byweight, it may be difficult to maintain the film strength of thephotoconductive layer. On the other hand, when it is more than 100 partsby weight, the electrostatic characteristics may decrease and the imageforming performance may degrade to result in the formation of poorduplicated image.

The inorganic photoconductive substance which can be used in the presentinvention includes zinc oxide, titanium oxide, zinc sulfide, cadmiumsulfide, cadmium carbonate, zinc selenide, cadmium selenide, telluriumselenide, and lead sulfide.

As the spectral sensitizing dye according to the present invention,various dyes can be employed individually or as a combination of two ormore thereof. Examples of the spectral sensitizing dyes are carboniumdyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes,phthalein dyes, polymethine dyes (e.g., oxonol dyes, merocyanine dyes,cyanine dyes, rhodacyanine dyes, and styryl dyes), and phthalocyaninedyes (including metallized dyes). Reference can be made to, for example,in Harumi Miyamoto and Hidehiko Takei, Imaging, 1973, No. 8, 12, C. J.Young et al., RCA Review, 15, 469 (1954), Kohei Kiyota et al.,Denkitsushin Gakkai Ronbunshi, J 63-C, No. 2, 97 (1980), Yuji Harasakiet al., Kogyo Kagaku Zasshi, 66, 78 and 188 (1963), and Tadaaki Tani,Nihon Shashin Gakkaishi, 35, 208 (1972).

Specific examples of the carbonium dyes, triphenylmethane dyes, xanthenedyes, and phthalein dyes are described, for example, in JP-B-51-452,JP-A-50-90334, JP-A-50-114227, JP-A-53-39130, JP-A-53-82353, U.S. Pat.Nos. 3,052,540 and 4,054,450, and JP-A-57-16456.

The polymethine dyes, such as oxonol dyes, merocyanine dyes, cyaninedyes, and rhodacyanine dyes, include those described, for example, in F.M. Hamer, The Cyanine Dyes and Related Compounds. Specific examplesinclude those described, for example, in U.S. Pat. Nos. 3,047,384,3,110,591, 3,121,008, 3,125,447, 3,128,179, 3,132,942, and 3,622,317,British Patents 1,226,892, 1,309,274 and 1,405,898, JP-B-48-7814 andJP-B-55-18892.

In addition, polymethine dyes capable of spectrally sensitizing in thelonger wavelength region of 700 nm or more, i.e., from the near infraredregion to the infrared region, include those described, for example, inJP-A-47-840, JP-A-47-44180, JP-B-51-41061, JP-A-49-5034, JP-A-49-45122,JP-A-57-46245, JP-A-56-35141, JP-A-57-157254, JP-A-61-26044,JP-A-61-27551, U.S. Pat. Nos. 3,619,154 and 4,175,956, and Researchdisclosure, 216,117 to 118 (1982).

The electrophotographic light-sensitive material of the presentinvention is excellent in that the performance properties thereof arenot liable to vary even when various kinds of sensitizing dyes areemployed together.

If desired, the photoconductive layer may further contain variousadditives commonly employed in conventional electrophotographiclight-sensitive layer, such as chemical sensitizers. Examples of suchadditives include electron-accepting compounds (e.g., halogen,benzoquinone, chloranil, acid anhydrides, and organic carboxylic acids)as described in the abovementioned Imaging, 1973, No. 8, 12; andpolyarylalkane compounds, hindered phenol compounds, andp-phenylene-diamine compounds as described in Hiroshi Kokado et al.,Saikin-no Kododen Zairyo to Kankotai no Kaihatsu Jitsuyoka, Chaps. 4 to6, Nippon Kagaku Joho K. K. (1986).

The amount of these additives is not particularly restricted and usuallyranges from 0.0001 to 2.0 parts by weight per 100 parts by weight of thephotoconductive substance.

The photoconductive layer suitably has a thickness of from 1 to 100 μm,preferably from 10 to 50 μm.

In cases where the photoconductive layer functions as a chargegenerating layer in a laminated light-sensitive material composed of acharge generating layer and a charge transporting layer, the thicknessof the charge generating layer suitably ranges from 0.01 to 1 μm,preferably from 0.05 to 0.5 μm.

If desired, an insulating layer can be provided on the light-sensitivelayer of the present invention. When the insulating layer is made toserve for the main purposes for protection and improvement of durabilityand dark decay characteristics of the light-sensitive material, itsthickness is relatively small. When the insulating layer is formed toprovide the light-sensitive material suitable for application to specialelectrophotographic processes, its thickness is relatively large,usually ranging from 5 to 70 μm, preferably from 10 to 50 μm.

Charge transporting materials in the above-described laminatedlight-sensitive material include polyvinylcarbazole, oxazole dyes,pyrazoline dyes, and triphenylmethane dyes. The thickness of the chargetransporting layer ranges usually from 5 to 40 μm, preferably from 10 to30 μm.

Resins to be used in the insulating layer or charge transporting layertypically include thermoplastic and thermoserring resins, e.g.,polystyrene resins, polyester resins, cellulose resins, polyetherresins, vinyl chloride resins, vinyl acetate resins, vinylchloride-vinyl acetate copolymer resins, polyacrylate resins, polyolefinresins, urethane resins, epoxy resins, melamine resins, and siliconeresins.

The photoconductive layer according to the present invention can beprovided on any known support. In general, a support for anelectrophotographic lightsensitive layer is preferably electricallyconductive. Any of conventionally employed conductive supports may beutilized in the present invention. Examples of usable conductivesupports include a substrate (e.g., a metal sheet, paper, and a plasticsheet) having been rendered electrically conductive by, for example,impregnating with a low resistant substance; the above-describedsubstrate with the back side thereof (opposite to the light-sensitivelayer side) being rendered conductive and having further coated thereonat least one layer for the purpose of prevention of curling; theabove-described substrate having provided thereon a water-resistantadhesive layer; the above-described substrate having provided thereon atleast one precoat layer; and paper laminated with a conductive plasticfilm on which aluminum is vapor deposited.

Specific examples of conductive supports and materials for impartingconductivity are described, for example, in Yukio Sakamoto,Denshishashin, 14, No. 1, pp. 2 to 11 (1975), Hiroyuki Moriga, NyumonTokushushi no Kaqaku, Kobunshi Kankokai (1975), and M. F. Hoover, J.Macromol. Sci. Chem., A-4(6), pp. 1327 to 1417 (1970).

The electrophotographic light-sensitive material according to thepresent invention can be utilized in any known electrophotographicprocess. Specifically, the light-sensitive material of the presentinvention is employed in any recording system including a PPC system anda CPC system in combination with any developer including a dry typedeveloper and a liquid developer. In particular, the light-sensitivematerial is preferably employed in combination with a liquid developerin order to obtain the excellent effect of the present invention sincethe light-sensitive material is capable of providing faithfullyduplicated image of highly accurate original.

Further, a color duplicated image can be produced by using it incombination with a color developer in addition to the formation of blackand white image. Reference can be made to methods described, forexample, in Kuro Takizawa, Shashin Kogyo, 33, 34 (1975) and MasayasuAnzai, Denshitsushin Gakkai Gi,jutsu Kenkyu Hokoku, 77, 17 (1977):

Moreover, the light-sensitive material of the present invention iseffective for recent other systems utilizing an electrophotographicprocess. For instance, the light-sensitive material containingphotoconductive zinc oxide as a photoconductive substance is employed asan offset printing plate precursor, and the lightsensitive materialcontaining photoconductive zinc oxide or titanium oxide which does notcause environmental pollution and has good whiteness is employed as arecording material for forming a block copy usable in an offset printingprocess or a color proof.

BEST MODE FOR CONDUCTING THE INVENTION

The present invention is illustrated in greater detail with reference tothe following examples, but the present invention is not to be construedas being limited thereto.

Synthesis examples of the resin (A) are specifically illustrated below.

SYNTHESIS EXAMPLE 1 OF RESIN (A): Resin (A-1)

A mixed solution of 95 g of benzyl methacrylate, 5 g of acrylic acid,and 200 g of toluene was heated to 90° C. under nitrogen gas stream, and6.0 g of 2,2'-azo-bisisobutyronitrile (abbreviated as AIBN) was addedthereto to effect a reaction for 4 hours. To the reaction mixture wasfurther added 2 g of AIBN, followed by reacting for 2 hours. Theresulting resin (A-1) had a weight average molecular weight (Mw) of8,500. The weight average molecular weight (Mw) was a value measured bythe GPC method and calculated in terms of polystyrene (hereinafter thesame). ##STR22##

SYNTHESIS EXAMPLES 2 TO 28 OF RESIN (A): Resins (A-2) to (A-28)

Each of Resins (A-2) to (A-28) shown in Table 1 below was synthesizedunder the same polymerization conditions as described in SynthesisExample 1 of Resin (A). A weight average molecular weight of each of theresins (A) was in a range of from 5.0×10³ to 9.0×10³.

                                      TABLE 1                                     __________________________________________________________________________     ##STR23##                                                                    Synthesis                                                                     Example of                                                                    Resin (A)                                                                            Resin (A)                                                                           R.sub.14         Y.sub.1                 x/y (weight             __________________________________________________________________________                                                          ratio)                   2     A-2   CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR24##              94/6                     3     A-3                                                                                  ##STR25##                                                                                      ##STR26##              95/5                     4     A-4   C.sub.6 H.sub.5                                                                                 ##STR27##              95/5                     5     A-5   CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR28##              97/3                     6     A-6                                                                                  ##STR29##                                                                                      ##STR30##              95/5                     7     A-7                                                                                  ##STR31##                                                                                      ##STR32##              94/6                     8     A-8                                                                                  ##STR33##                                                                                      ##STR34##              95/5                     9     A-9   CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR35##              93/7                    10     A-10                                                                                 ##STR36##                                                                                      ##STR37##              95/5                    11     A-11                                                                                 ##STR38##                                                                                      ##STR39##              96/4                    12     A-12                                                                                 ##STR40##                                                                                      ##STR41##              97/3                    13     A-13                                                                                 ##STR42##                                                                                      ##STR43##              97/3                    14     A-14                                                                                 ##STR44##                                                                                      ##STR45##              94/6                    15     A-15                                                                                 ##STR46##                                                                                      ##STR47##              97/3                    16     A-16                                                                                 ##STR48##                                                                                      ##STR49##              95/5                    17     A-17                                                                                 ##STR50##                                                                                      ##STR51##              93/7                    18     A-18                                                                                 ##STR52##                                                                                      ##STR53##              97/3                    19     A-19                                                                                 ##STR54##                                                                                      ##STR55##              95/5                    20     A-20                                                                                 ##STR56##                                                                                      ##STR57##              98/2                    21     A-21                                                                                 ##STR58##                                                                                      ##STR59##              96/4                    22     A-22  CH.sub.2 C.sub.6 H.sub.5                                                                        ##STR60##              97/3                    23     A-23                                                                                 ##STR61##                                                                                      ##STR62##              94/6                    24     A-24                                                                                 ##STR63##                                                                                      ##STR64##              95/5                    25     A-25                                                                                 ##STR65##                                                                                      ##STR66##              92/8                    26     A-26                                                                                 ##STR67##                                                                                      ##STR68##              97/3                    27     A-27                                                                                 ##STR69##                                                                                      ##STR70##              95/5                    28     A-28                                                                                 ##STR71##                                                                                      ##STR72##              95/5                    __________________________________________________________________________

SYNTHESIS EXAMPLE 29 OF RESIN (A): Resin (A-29)

A mixed solution of 95 g of 2,6-dichlorophenyl methacrylate, 5 g ofacrylic acid, 2 g of n-dodecylmercaptan, and 200 g of toluene was heatedto a temperature of 80° C under nitrogen gas stream, and 2 g of AIBN wasadded thereto to effect reaction for 4 hours. Then, 0.5 g of AIBN wasadded thereto, followed by reacting for 2 hours, and thereafter 0.5 g ofAIBN was added thereto, followed by reacting for 3 hours. After cooling,the reaction mixture was poured into 2 liters of a solvent mixture ofmethanol and water (9:1) to reprecipitate, and the precipitate wascollected by decantation and dried under reduced pressure to obtain 78 gof the copolymer in the wax form having a weight average molecularweight of 6.3×10³.

SYNTHESIS EXAMPLES 30 TO 33 OF RESIN (A): Resins (A-30) to (A-33).

Copolymers shown in Table 2 below were synthesized in the same manner asdescribed in Synthesis Example 29 of Resin (A), respectively. A weightaverage molecular weight of each of the polymers was in a range of from6×10³ to 8×10³.

                  TABLE 2                                                         ______________________________________                                         ##STR73##                                                                    Synthesis                           x/y                                       Example of                                                                            Resin                       (weight                                   Resin (A)                                                                             (A)      Y                  ratio)                                    ______________________________________                                        30      A-30                                                                                    ##STR74##         90/5                                      31      A-31                                                                                    ##STR75##         92/3                                      32      A-32                                                                                    ##STR76##         88/7                                      33      A-33                                                                                    ##STR77##         90/5                                      ______________________________________                                    

SYNTHESIS EXAMPLE 101 OF RESIN (A): Resin (A-101)

A mixed solution of 96 g of benzyl methacrylate, 4 g of thiosalicylicacid, and 200 g of toluene was heated to a temperature of 75° C. undernitrogen gas stream, and 1.0 g of 2,2'-azobisisobutyronitrile(abbreviated as AIBN ) was added thereto to effect reaction for 4 hours.To the reaction mixture was further added 0.4 g of AIBN, followed bystirring for 2 hours, and thereafter 0.2 g of AIBN was added thereto,followed by stirring for 3 hours. The resulting resin (A-101) had thefollowing structure and a weight average molecular weight of 6.8×10³.##STR78##

SYNTHESIS EXAMPLES 102 TO 113 OF RESIN (A): Resins (A-102) to (A-113)

Resins (A-102) to (A-113) were synthesized in the same manner asdescribed in Synthesis Example 101 of Resin (A), except for using themonomers described in Table 3 below in place of 96 g of benzylmethacrylate, respectively. A weight average molecular weight of each ofthese resins was in a range of from 6.0×10³ to 8×10³.

                                      TABLE 3                                     __________________________________________________________________________     ##STR79##                                                                    Synthesis                                                                     Example of                                                                    Resin (A)                                                                           Resin (A)                                                                           R.sub.17       Y.sub.1             x/y (weight                    __________________________________________________________________________                                                   ratio)                         102   A-102 C.sub.2 H.sub.5                                                                               ##STR80##          94/2                           103   A-103 C.sub.6 H.sub.5                                                                               ##STR81##          94/2                           104   A-104                                                                                ##STR82##                                                                                    ##STR83##          94.5/1.5                       105   A-105                                                                                ##STR84##                                                                                    ##STR85##          94/2                           106   A-106 CH.sub.2 C.sub.6 H.sub.5                                                                      ##STR86##          93.5/2.5                       107   A-107 C.sub.2 H.sub.5                                                                               ##STR87##          93/3                           108   A-108                                                                                ##STR88##                                                                                    ##STR89##           85/11                         109   A-109                                                                                ##STR90##     --                  96/0                           110   A-110                                                                                ##STR91##                                                                                    ##STR92##          92/4                           111   A-111                                                                                ##STR93##                                                                                    ##STR94##          94.5/1.5                       112   A-112                                                                                ##STR95##                                                                                    ##STR96##           76/20                         113   A-113 (CH.sub.2 ).sub.2OC.sub.6 H.sub.5                                                            --                  96/0                           __________________________________________________________________________

SYNTHESIS EXAMPLES 114 TO 124 OF RESIN (A): Resins (A-114) to (A-124)

Resins (A-114) to (A-124) were synthesized under the same reactionconditions as described in Synthesis Example 101 of Resin (A), exceptfor using the methacrylates and mercapto compounds described in Table 4below in place of 96 g of benzyl methacrylate and 4 g of thiosalicylicacid and replacing 200 g of toluene with 150 g of toluene and 50 g ofisopropanol, respectively.

                                      TABLE 4                                     __________________________________________________________________________     ##STR97##                                                                    Synthesis                                                                     Example of                                            Weight Average          Resin (A)                                                                           Resin (A)                                                                           W                  Amount                                                                              R.sub.18   Amount                                                                              Molecular               __________________________________________________________________________                                                          Weight                  114   A-114 HOOCCH.sub.2 CH.sub.2 CH.sub.2                                                                   4 g   C.sub.2 H.sub.5                                                                          96 g  7.3 ×                                                                   10.sup.3                115   A-115 HOOCCH.sub.2       5 g   C.sub.3 H.sub.7                                                                          95 g  5.8 ×                                                                   10.sup.3                116   A-116                                                                                ##STR98##         5 g   CH.sub.2 C.sub.6 H.sub.5                                                                 95 g  7.5 ×                                                                   10.sup.3                117   A-117 HOOCCH.sub.2 CH.sub.2                                                                            5.5 g C.sub.6 H.sub.5                                                                          94.5 g                                                                              6.5 ×                                                                   10.sup.3                118   A-118 HOOCCH.sub.2       4 g                                                                                  ##STR99## 96 g  5.3 ×                                                                   10.sup.3                119   A-119                                                                                ##STR100##        3 g                                                                                  ##STR101##                                                                              97 g  6.6 ×                                                                   10.sup.3                120   A-120 HO.sub.3 SCH.sub.2 CH.sub.2                                                                      3 g                                                                                  ##STR102##                                                                              97 g  8.8 ×                                                                   10.sup.3                121   A-121                                                                                ##STR103##        4 g                                                                                  ##STR104##                                                                              96 g  7.5 ×                                                                   10.sup.3                122   A-122                                                                                ##STR105##        7 g                                                                                  ##STR106##                                                                              93 g  5.5 ×                                                                   10.sup.3                123   A-123                                                                                ##STR107##        6 g                                                                                  ##STR108##                                                                              94 g  4.5 ×                                                                   10.sup.3                124   A-124                                                                                ##STR109##        4 g                                                                                  ##STR110##                                                                              96 g  5.6 ×             __________________________________________________________________________                                                          10.sup.3            

SYNTHESIS EXAMPLE 125 OF RESIN (A): Resin (A-125)

A mixed solution of 100 g of 1-naphthyl methacrylate, 150 g of tolueneand 50 g of isopropanol was heated to a temperature of 80° C. undernitrogen gas stream, and 5.0 g of 4,4'-azobis(4-cyanovaleric acid)(abbreviated as ACV) was added thereto, followed by reacting withstirring for 5 hours. Then, 1 g of ACV was added thereto, followed byreacting with stirring for 2 hours, and thereafter 1 g of ACV was addedthereto, followed by reacting with stirring for 3 hours. The resultingpolymer had a weight average molecular weight of 7.5×10³. ##STR111##

SYNTHESIS EXAMPLE 126 OF RESIN (A): Resin (A-126)

A mixed solution of 50 .g of methyl methacrylate and 150 g of methylenechloride was cooled to -20° C. under nitrogen gas stream, and 1.0 g of a10% hexane solution of 1,1-diphenylhexyl lithium prepared just beforewas added thereto, followed by stirring for 5 hours. Carbon dioxide waspassed through the mixture at a flow rate of 10 ml/cc for 10 minuteswith stirring, the cooling was discontinued, and the reaction mixturewas allowed to stand to room temperature with stirring. Then, thereaction mixture was added to a solution of 50 ml of 1N hydrochloricacid in 1 liter of methanol to precipitate, and the white powder wascollected by filtration. The powder was washed with water until thewashings became neutral, and dried under reduced pressure to obtain 18 gof the polymer having a weight average molecular weight of 6.5×10³.##STR112##

SYNTHESIS EXAMPLE 127 OF RESIN (A): Resin (A-127)

A mixed solution of 97 g of benzyl methacrylate, 3 g of acrylic acid,9.7 g of Initiator (I-1) shown below and 100 g of tetrahydrofuran washeated to a temperature of 50° C. under nitrogen gas stream. ##STR113##

The solution was irradiated with light from a high-pressure mercury lampof 400 W at a distance of 10 cm through a glass filter for 12 hours toconduct a photopolymerization reaction. The reaction mixture obtainedwas reprecipitated in one liter of n-hexane, and the precipitates formedwere collected and dried to obtain 75 g of the polymer having a weightaverage molecular weight of 8×10³. ##STR114##

SYNTHESIS EXAMPLES 128 TO 133 OF RESIN (A): Resins (A-128) to (A-133)

Each of resins (A) shown in Table 5 below was synthesized in the sameprocedure as described in Synthesis Example 127 of Resin (A) except forusing 97 g of a monomer corresponding to the polymer component shown inTable 5 below and 0,044 moles of the initiator (I) shown in Table 5below in place of 97 g of benzyl methacrylate and 9.7 g of Initiator(I-1), respectively. The weight average molecular weight of each of thepolymers was in a range of from 7×10³ to 9×10³.

                                      TABLE 5                                     __________________________________________________________________________     ##STR115##                                                                   Synthesis                                                                     Example of                                                                    Resin (A)                                                                           Resin (A)                                                                             Initiator (I)                                                   __________________________________________________________________________    128   A-128                                                                                  ##STR116##                                                     129   A-129                                                                                  ##STR117##                                                     130   A-130                                                                                  ##STR118##                                                     131   A-131                                                                                  ##STR119##                                                     132   A-132                                                                                  ##STR120##                                                     133   A-133                                                                                  ##STR121##                                                     __________________________________________________________________________    Synthesis                                                                     Example of                                                                    Resin (A)                                                                           R.sup.30       R.sup.31                                                                             X                                                 __________________________________________________________________________    128                                                                                  ##STR122##                                                                                   ##STR123##                                                                           ##STR124##                                       129                                                                                  ##STR125##    CH.sub.2 C.sub.6 H.sub.5                                                              ##STR126##                                       130                                                                                  ##STR127##                                                                                   ##STR128##                                                                           ##STR129##                                       131                                                                                  ##STR130##    C.sub.6 H.sub.5                                                                       ##STR131##                                       132                                                                                  ##STR132##    C.sub.2 H.sub.5                                                                       ##STR133##                                       133                                                                                  ##STR134##    CH.sub.2 C.sub.6 H.sub.5                                                              ##STR135##                                       __________________________________________________________________________

SYNTHESIS EXAMPLE 201 OF RESIN (A): Resin (A-201)

A mixed solution of 95 g of ethyl methacrylate, and 200 g oftetrahydrofuran was sufficiently degassed under nitrogen gas stream andcooled to -20° C. Then, 1.5 g of 1,1-diphenylbutyl lithium was added tothe mixture, and the reaction was conducted for 12 hours. Furthermore, amixed solution of 5 g of triphenylmethyl methacrylate and 5 g oftetrahydrofuran was sufficiently degassed under nitrogen gas stream,and, after adding the mixed solution to the above described mixture, thereaction was further conducted for 8 hours. The mixture was adjusted to0° C. and after adding thereto 10 ml of methanol, the reaction wasconducted for 30 minutes and the polymerization was terminated. Thetemperature of the polymer solution obtained was adjusted at atemperature of 30° C. under stirring and, after adding thereto 3 ml ofan ethanol solution of 30% hydrogen chloride, the resulting mixture wasstirred for one hour. Then, the solvent of the reaction mixture wasdistilled off under reduced pressure until the whole volume was reducedto a half, and then the mixture was reprecipitated from one liter ofpetroleum ether. The precipitates formed were collected and dried underreduced pressure to obtain 70 g of the polymer having a weight averagemolecular weight (Mw) of 8.5×10³. ##STR136##

SYNTHESIS EXAMPLE 202 OF RESIN (A): Resin (A-202)

A mixed solution of 46 g of n-butyl methacrylate, 0.5 g of (tetraphenylprophynato) aluminum methyl, and 60 g of methylene chloride was raisedto a temperature of 30° C. under nitrogen gas stream. The mixture wasirradiated with light from a xenon lamp of 300 W at a distance of 25 cmthrough a glass filter, and the reaction was conducted for 12 hours. Tothe mixture was further added 4 g of benzyl methacrylate, afterlight-irradiating in the same manner as above for 8 hours, 3 g ofmethanol was added to the reaction mixture followed by stirring for 30minutes, and the reaction was terminated. Then, Pd-C was added to thereaction mixture, and a catalytic reduction reaction was conducted forone hour at a temperature of 25° C. After removing insoluble substancesfrom the reaction mixture by filtration, the reaction mixture wasreprecipitated from 500 ml of petroleum ether and the precipitatesformed were collected and dried to obtain 33 g of the polymer having anMw of 9.3×10³. ##STR137##

SYNTHESIS EXAMPLE 203 OF RESIN (A): Resin (A-203)

A mixed solution of 90 g of 2-chloro-6-methylphenyl methacrylate and 200g of toluene was sufficiently degassed under nitrogen gas stream andcooled to 0° C. Then, 2.5 g of 1,1-diphenyl-3-methylpentyl lithium wasadded to the mixture followed by stirring for 6 hours. Further, 25.4 gof 4-vinylbenzenecarboxylic acid triisopropylsilyl ester was added tothe mixture and, after stirring the mixture for 6 hours, 3 g of methanolwas added to the mixture followed by stirring for 30 minutes. Then, tothe reaction mixture was added 10 g of an ethanol solution of 30%hydrogen chloride and, after stirring the mixture at 25° C. for onehour, the mixture was reprecipitated from one liter of petroleum ether.The precipitates thus formed were collected, washed twice with 300 ml ofdiethyl ether and dried to obtain 58 g of the polymer having an Mw of7.8×10³. ##STR138##

SYNTHESIS EXAMPLE 204 OF RESIN (A): Resin (A-204)

A mixture of 95 g of phenyl methacrylate and 4.8 g of benzylN,N-diethyldithiocarbamate was placed in a vessel under nitrogen gasstream followed by closing the vessel and heated to a temperature of 60°C. The mixture was irradiated with light from a high-pressure mercurylamp of 400 W at a distance of 10 cm through a glass filter for 10 hoursto conduct phqtopolymerization. Then, 5 g of acrylic acid and 180 g ofmethyl ethyl ketone were added to the mixture and, after replacing thegas in the vessel with nitrogen, the mixture was light-irradiated againfor 10 hours. The reaction mixture was reprecipitated from 1.5 liters ofhexane and the precipitates formed were collected and dried to obtain 68g of the polymer having an Mw of 9.5×10³. ##STR139##

SYNTHESIS EXAMPLES 205 TO 218 OF RESIN (A): Resins (A-205) to (A-218)

Each of resins (A). shown in Table 6 below was synthesized in the samemanner as described in Synthesis Example 201 of Resin (A) above, The Mwof each of the resins was in a range of from 6×10³ to 9.5×10³.

                                      TABLE 6                                     __________________________________________________________________________     ##STR140##                                                                   Synthesis                                                                     Example of                                                                    Resin (A)                                                                           Resin (A)                                                                           R.sub.0        Y                  x/y                             __________________________________________________________________________    205   A-205                                                                                ##STR141##                                                                                   ##STR142##        96/4                            206   A-206                                                                                ##STR143##                                                                                   ##STR144##        96/4                            207   A-207                                                                                ##STR145##                                                                                   ##STR146##        95/5                            208   A-208                                                                                ##STR147##                                                                                   ##STR148##        92/8                            209   A-209                                                                                ##STR149##                                                                                   ##STR150##        95/5                            210   A-210                                                                                ##STR151##                                                                                   ##STR152##        97/3                            211   A-211                                                                                ##STR153##                                                                                   ##STR154##         90/10                          212   A-212                                                                                ##STR155##                                                                                   ##STR156##        98/2                            213   A-213                                                                                ##STR157##                                                                                   ##STR158##        95/5                            214   A-214                                                                                ##STR159##                                                                                   ##STR160##        94/6                            215   A-215                                                                                ##STR161##                                                                                   ##STR162##        94/6                            216   A-216                                                                                ##STR163##                                                                                   ##STR164##        95/5                            217   A-217 C.sub.3 H.sub.7                                                                               ##STR165##        95/5                            218   A-218 CH.sub.2 C.sub.6 H.sub.5                                                                      ##STR166##        96/4                            __________________________________________________________________________

SYNTHESIS EXAMPLES 219 TO 223 OF RESIN (A): Resins (A-219) to (A-223)

Each of the resins (A) shown in Table 7 below was synthesized in thesame manner as described in synthesis Example 204 of Resin (A) above.The Mw of each of the resins was in a range of from 8×10³ to 1×10⁴.

                                      TABLE 7                                     __________________________________________________________________________     ##STR167##                                                                   Synthesis                                                                     Example of                                             x/y/z                  Resin (A)                                                                           Resin (A)                                                                             R.sub.0    X           Y                 (weight                __________________________________________________________________________                                                           ratio)                 219   A-219   CH.sub.3                                                                                  ##STR168##                                                                                ##STR169##       65/30/5                220   A-220   C.sub.2 H.sub.5                                                                           ##STR170##                                                                                ##STR171##       75/25/3                221   A-221                                                                                  ##STR172##                                                                               ##STR173##                                                                                ##STR174##       81/15/4                222   A-222                                                                                  ##STR175##                                                                               ##STR176##                                                                                ##STR177##       75/20/5                223   A-223                                                                                  ##STR178##                                                                               ##STR179##                                                                                ##STR180##       75/20/5                __________________________________________________________________________

Synthesis examples of the resin (B) are specifically illustrated below.

SYNTHESIS EXAMPLE 1 OF RESIN (B): Resin (B-1)

A mixed solution of 100 g of methyl methacrylate and 200 g oftetrahydrofuran was sufficiently degassed under nitrogen gas stream andcooled to -20° C. Then, 0.8 g of 1,1-diphenylbutyl lithium was added tothe mixture, and the reaction was conducted for 12 hours. Furthermore, amixed solution of 60 g of methyl acrylate, 6 g of triphenylmethylmethacrylate and 5 g of tetrahydrofuran was sufficiently degassed undernitrogen gas stream, and, after adding the mixed solution to the abovedescribed mixture, the reaction was further conducted for 8 hours. Themixture was adjusted to 0° C. and after adding thereto 10 ml ofmethanol, the reaction was conducted for 30 minutes and thepolymerization was terminated. The temperature of the polymer solutionobtained was adjusted at 30° C. under stirring and, after adding thereto3 ml of an ethanol solution of 30% hydrogen chloride, the resultingmixture was stirred for one hour. Then, the solvent of the reactionmixture was distilled off under reduced pressure until the whole volumewas reduced to a half, and then the mixture was reprecipitated from oneliter of petroleum ether.

The precipitates formed were collected and dried under reduced pressureto obtain 72 g of the polymer having an Mw of 7.3×10⁴. ##STR181##

SYNTHESIS EXAMPLE 2 OF RESIN (B): Resin (B-2)

A mixed solution of 70 g of methyl methacrylate, 30 g of methylacrylate, 0.5 g of (tetraphenyl prophynato) aluminum methyl, and 60 g ofmethylene chloride was raised to a temperature of 30° C. under nitrogengas stream. The mixture was irradiated with light from a xenon lamp of300 W at a distance of 25 cm through a glass filter, and the reactionwas conducted for 12 hours. To the mixture were further added 60 g ofmethyl acrylate and 3.2 g of benzyl methacrylate, and, afterlight-irradiating in the same manner as above for 8 hours, 3 g ofmethanol was added to the reaction mixture followed by stirring for 30minutes, and the reaction was terminated. Then, Pd-C was added to thereaction mixture, and a catalytic reduction reaction was conducted forone hour at 25° C.

After removing insoluble substances from the reaction mixture byfiltration, the reaction mixture was reprecipitated from 500 ml ofpetroleum ether and the precipitates formed were collected and dried toobtain 118 g of the resin having an Mw of 8×10⁴. ##STR182##

SYNTHESIS EXAMPLE 3 OF RESIN (B): Resin (B-3)

A mixed solution of 100 g of ethyl methacrylate and 200 g of toluene wassufficiently degassed under nitrogen gas stream and cooled to 0° C.Then, 2.5 g of 1,1-diphenyl-3-methylpentyl lithium was added to themixture followed by stirring for 6 hours. Further, 60 g of methylmethacrylate and 11.7 g of 4-vinylbenzenecarboxylic acidtriisopropylsilyl ester were added to the mixture and, after stirringthe mixture for 6 hours, 3 g of methanol was added to the mixturefollowed by stirring for 30 minutes.

Then, to the reaction mixture was added 10 g of an ethanol solution of30% hydrogen chloride and, after stirring the mixture at 25° C. for onehour, the mixture was reprecipitated from one liter of methanol. Theprecipitates thus formed were collected, washed twice with 300 ml ofmethanol and dried to obtain 121 g of the polymer having an Mw of6.5×10⁴. ##STR183##

SYNTHESIS EXAMPLE 4 OF RESIN (B): Resin (B-4)

A mixture of 67 g of methyl methacrylate and 4.8 g of benzylN,N-diethyldithiocarbamate was placed in a vessel under nitrogen gasstream followed by closing the vessel and heated to a temperature of 50°C. The mixture was irradiated with .light from a high-pressure mercurylamp of 400 W at a distance of 10 cm through a glass filter for 6 hoursto conduct photopolymerization.

Then, 32 g of methyl acrylate, 1 g of acrylic acid and 180 g of methylethyl ketone were added to the mixture and, after replacing the gas inthe vessel with nitrogen, the mixture was light-irradiated again for 10hours. The reaction mixture was reprecipitated from one liter ofmethanol and the precipitates formed were collected and dried to obtain73 g of the polymer having an Mw of 4.8×10⁴. ##STR184##

SYNTHESIS EXAMPLE 5 OF RESIN (B): Resin (B-5).

A mixture of 50 g of methyl methacrylate, 25 g of ethyl methacrylate and1.0 g of benzyl isopropyl-xanthate was placed in a vessel under nitrogengas stream followed by closing the vessel and heated to a temperature of50° C. The mixture was irradiated with light from a high-pressuremercury lamp of 400 W at a distance of 10 cm through a glass filter for6 hours to conduct photopolymerization. The polymerization product wasdissolved in tetrahydrofuran to make a 40% solution, then 22 g of methylacrylate was added thereto and, after replacing the gas in the vesselwith nitrogen, the mixture was light-irradiated again for 10 hours.

Then, 3 g of 2-(2'-carboxyethyl)carboxyloxyethyl methacrylate was addedto the mixture and, after replacing the gas in the vessel with nitrogen,the mixture was light-irradiated again for 8 hours. The reaction mixturewas reprecipitated from 2 liters of methanol and the powder collectedwas dried to obtain 63 g of the polymer having an Mw of 6×10⁴.##STR185##

SYNTHESIS EXAMPLE 6 OF RESIN (B): Resin (B-6)

A mixed solution of 97 g of ethyl acrylate, 3 g of methacrylic acid, 2 gof 2-mercaptoethanol and 200 g of tetrahydrofuran was heated to 60° C.under nitrogen gas stream with stirring, and 1.0 g of2,2'-azobisisovaleronitrile (abbreviated as AIVN) was added thereto toeffect a reaction for 4 hours. To the reaction mixture was further added0.5 g of AIVN, followed by reacting for 4 hours. The temperature of thereaction mixture was adjusted at 20° C., then a mixed solution of 8.6 gof 4,4'-azobis(4-cyanovaleric acid), 12 g of dicyclohexylcarbodiimide,0.2 g of 4-(N,N-dimethylamino)pyridine and 30 g of tetrahydrofuran wasadded dropwise thereto over a period of one hour. After further stirringfor 2 hours, 5 g of a 85% aqueous formic acid solution was addedthereto, followed by stirring for 30 minutes. The crystalsthus-deposited were removed by filtration, the liltrate was distilledunder reduced pressure at a temperature of 25° C. to remove the solvent.The polymer thus-obtained (polymer initiator) shown below had an Mw of6.3×10³. ##STR186##

A mixed solution of 70 g of methyl methacrylate and 170 g of toluene washeated to 70° C. under nitrogen gas stream with stirring. A solutionprepared by dissolving 30 g of the above described polymer initiator in30 g of toluene and replacing the gas in the vessel with nitrogen wasadded to the above mixed solution, followed by reacting for 8 hours. Thepolymer formed was reprecipitated from 2 liters of methanol and thepowder collected was dried to obtain 72 g of the polymer having an Mw of4×10⁴. ##STR187##

SYNTHESIS EXAMPLES 7 TO 16 OF RESIN (B): Resins (B-7) to (B-16)

Each of the resins (B) shown in Table 8 below was synthesized in thesame reaction procedure as described in Synthesis Example 3 of Resin(B). The Mw of each of the resins obtained was in a range of from 5×10⁴to 9×10⁴.

    TABLE 8      ##STR188##       Synthesis        Examples of       p/q/r/y/z Resin (B) Resin (B)     R.sup.32 X.sub.1 R.sup.33 Y.sub.2 Z.sub.3 (weight ratio)      7 B-7 CH.sub.3 -- CH.sub.3 --     ##STR189##      65/0/32/0/3   8 B-8 CH.sub.3 -- C.sub.2      H.sub.5 --     ##STR190##      72/0/25/0/3      9 B-9 CH.sub.3     ##STR191##      CH.sub.3      ##STR192##      ##STR193##      66/10/20/3/1  10 B-10 C.sub.2      H.sub.5     ##STR194##      CH.sub.3 --      ##STR195##      74.2/10/15/0/0.8  11 B-11 C.sub.3      H.sub.7     ##STR196##      CH.sub.3      ##STR197##      ##STR198##      61/10/20/8/1.0      12 B-12 CH.sub.3     ##STR199##      CH.sub.3      ##STR200##      ##STR201##      59/10/20/10/1.0  13 B-13  CH.sub.3 -- C.sub.2      H.sub.5 --     ##STR202##      81/0/15/0/4  14 B-14 C.sub.6      H.sub.5     ##STR203##      CH.sub.3      ##STR204##      ##STR205##      30/20/45/3/2  15 B-15 CH.sub.2 C.sub.6      H.sub.5 -- CH.sub.3     ##STR206##      ##STR207##      75/0/15/6.5/3.5  16 B-16 CH.sub. 3 -- C.sub.2      H.sub.5     ##STR208##      ##STR209##      80/0/14/4/2

SYNTHESIS EXAMPLES 17 TO 23 OF RESIN (B): Resins (B-17) to (B-23)

Each of the resins (B) shown in Table 9 below was synthesized in thesame reaction procedure as described in Synthesis Example 4 of Resin(B). The Mw of each of the resins obtained was in a range of from 4×10⁴to 8×10⁴.

                                      TABLE 9                                     __________________________________________________________________________     ##STR210##                                                                   Syn-                                                                          thesis                                                                        Ex-                                                                           ample                                                                         of                                                                            Resin                                                                             Resin                                             k/l/m/n/q               (B) (B) X.sub.2   Y.sub.2          Z.sub.3            (weight                 __________________________________________________________________________                                                          ratio)                  17  B-17                                                                               ##STR211##                                                                              ##STR212##                                                                                     ##STR213##        64/15/15/4.8/1.2        18  B-18                                                                              --                                                                                       ##STR214##                                                                                     ##STR215##        70/0/20/9/1.0           19  B-19                                                                              --        --                                                                                              ##STR216##        67/0/31.5/0/1.5         20  B-20                                                                              --                                                                                       ##STR217##                                                                                     ##STR218##        65/0/28/6/1.0           21  B-21                                                                               ##STR219##                                                                              ##STR220##                                                                                     ##STR221##        53.4/10/30/5/1.6        22  B-22                                                                               ##STR222##                                                                              ##STR223##                                                                                     ##STR224##        64/5/20/10/1.0          23  B-23                                                                              --                                                                                       ##STR225##                                                                                     ##STR226##        70/0/25/3/2.0           __________________________________________________________________________

SYNTHESIS EXAMPLE 101 OF RESIN (B): Resin (B-101)

A mixture of 47.5 g of methyl acrylate, 2.5 g of acrylic acid, 7.6 g of2-carboxyethyl N,N-diethyldithiocarbamate (Initiator 1-101) and 50 g oftetrahydrofuran was placed in a Qessel under nitrogen gas stream and,after closing the vessel, heated to a temperature of 50° C. The mixturewas irradiated with light from a high-pressure mercury lamp for 400 W ata distance of 10 cm through a glass filter for 8 hours to conductphotopolymerization. The reaction mixture obtained was reprecipitatedfrom 500 ml of petroleum ether, and the precipitates formed werecollected and dried to obtain 41 g of the polymer having an Mw of1.0×10⁴.

A mixture of 10 g of the above described polymer (polymer initiator), 65g of methyl methacrylate, 25 g of methyl acrylate and 100 g oftetrahydrofuran was heated to a temperature of 50° C. under nitrogen gasstream and irradiated with light under the same condition as above for10 hours to conduct photopolymerization. The reaction mixture wasreprecipitated from one liter of methanol and the precipitates thusformed were collected and dried to obtain 85 g of the block polymerhaving an Mw of 8.5×10⁴. ##STR227##

SYNTHESIS EXAMPLE 102 OF RESIN (B): Resin (B-102)

A mixed solution of 67 g of methyl methacrylate, 33 g of methyl.acrylate, 2.2 g of benzyl N-ethyl-N-(2-carboxyethyl)dithiocarbamate(Initiator 1-102) and 100 g of tetrahydrofuran was heated to atemperature of 50° C. under nitrogen gas stream and irradiated withlight under the same condition as described in Synthesis Example 101 for8 hours to conduct photopolymerization. The reaction mixture wasreprecipitated from one liter of methanol and the precipitates formedwere collected and dried to obtain 85 g of the polymer having an Mw of8×10⁴. A mixture of 85 g of the above described polymer, 14 g of methylmethacrylate, 1 g of methacrylic acid and 150 g of tetrahydrofuran washeated to a temperature of 50 ° C. under nitrogen gas stream andirradiated with light under the same condition as described in SynthesisExample 101 for 16 hours to conduct photopolymerization. The reactionmixture was reprecipitated from one liter of methanol and theprecipitates formed were collected and dried to obtain 83 g of the blockpolymer having an Mw of 9.5×10⁴. ##STR228##

SYNTHESIS EXAMPLE 103 OF RESIN (B): Resin (B-103)

A mixed solution of 80 g of ethyl methacrylate and 200 g of toluene wassufficiently degassed under nitrogen gas stream and cooled to -20° C.Then, 2.0 g of 1,1-diphenyl-3-methylpentyl lithium was added to themixture followed by stirring for 12 hours. To the mixture were furtheradded 19 g of methyl methacrylate and 1.5 g of4-vinylphenylcarbonyloxytrimethylsilane, and the mixture was subjectedto reaction for 12 hours. Then, the mixture was reacted for 2 hoursunder carbon dioxide gas stream, followed by reacting at a temperatureof 0° C. for 2 hours. To the reaction mixture was added dropwise oneliter of a methanol solution containing 10 g of 30% hydrochloric acidwith stirring over a period of 30 minutes, followed by stirring for onehour. The powder thus deposited was collected by filtration, washed withmethanol and dried to obtain 75 g of the block polymer having an Mw of6.5×10⁴. ##STR229##

SYNTHESIS EXAMPLES 104 TO 113 OF RESIN (B): Resins (B-104) to (B-113)

Each of the resins (B) shown in Table 10 below was synthesized in thesame reaction procedure as described in Synthesis Example 102 of Resin(B). The Mw of each of the resins obtained was in a range of from 7×10⁴to 9×10⁴.

    TABLE 10      ##STR230##       Synthesis        Examples of       p/q/r/y/z Resin (B) Resin (B)     R.sup.41 X.sup.1 R.sub.2 Y.sup.1 Z.sup.1 (weight ratio)               104 B-104 CH.sub.3 -- CH.sub.3 --      ##STR231##      65/0/32/0/3  105 B-105 CH.sub.3 -- C.sub.2      H.sub.5 --     ##STR232##      72/0/25/0/3      106 B-106 CH.sub.3     ##STR233##      CH.sub.3      ##STR234##      ##STR235##      66/10/20/3/1  107 B-107 C.sub.2      H.sub.5     ##STR236##      CH.sub.3 --      ##STR237##      74.2/10/15/0/0.8  108 B-108 C.sub.3      H.sub.7     ##STR238##      CH.sub.3      ##STR239##      ##STR240##      61/10/20/8/1.0      109 B-109 CH.sub.3     ##STR241##      CH.sub.3      ##STR242##      ##STR243##      59/10/20/10/1.0  110 B-110 CH.sub.3 -- C.sub.2      H.sub.5 --     ##STR244##      81/0/15/0/4  111 B-111 C.sub.6      H.sub.5     ##STR245##      CH.sub.3      ##STR246##      ##STR247##      30/20/45/3/2  112 B-112 CH.sub.2 C.sub.6      H.sub.5 -- CH.sub.3     ##STR248##      ##STR249##      75/0/15/6.5/3.5  113 B-113 CH.sub.3 -- C.sub.2      H.sub.5     ##STR250##      ##STR251##      80/0/14/4/2

SYNTHESIS EXAMPLES 114 TO 120 OF RESIN (B): Resins (B-114) to (B-120)

Each of the block polymers shown in Table 11 below was synthesized inthe same manner as described in Synthesis Example 101 of Resin (B)except for using 4,2×10⁻³ moles of each of the initiators shown in Tablebelow in place of 7.6 g of initiator (I-101) used in Synthesis Example101 of Resin (B), The Mw of each of the resins was in a range of from8×10⁴ to 10×10⁴,

                                      TABLE 11                                    __________________________________________________________________________    Synthesis                                                                     Example of                                                                    Resin (B)                                                                           Resin (B)                                                                          Initiator                                                          __________________________________________________________________________    114   B-114                                                                              I-103                                                                             ##STR252##                                                     115   B-115                                                                              I-104                                                                             ##STR253##                                                     116   B-116                                                                              I-105                                                                             ##STR254##                                                     117   B-117                                                                              I-106                                                                             ##STR255##                                                     118   B-118                                                                              I-107                                                                             ##STR256##                                                     119   B-119                                                                              I-108                                                                             ##STR257##                                                     120   B-120                                                                              I-109                                                                             ##STR258##                                                     __________________________________________________________________________

SYNTHESIS EXAMPLES 121 TO 230 OF RESIN (B): Resins (B-121) to (B-130)

Each of the resins (B) shown in Table 12 below was synthesized by aphotopolymerization reaction in the same manner as described inSynthesis Example 102 of Resin (B). The Mw of each of the resins was ina range of from 6×10⁴ to 8×10⁴.

    TABLE 12      ##STR259##       Synthesis        Example of Resin      k/l/m/n/o Resin (B) (B) R.sub.1 W      X.sup.2 Y.sup.2 Z.sup.2 (weight ratio)               121 B-121 C.sub.4      H.sub.9     ##STR260##      ##STR261##      ##STR262##      ##STR263##      64/15/15/4.8/1.2  122 B-122 C.sub.4      H.sub.9     ##STR264##      --      ##STR265##      ##STR266##      70/0/20/9/1.0  123 B-123 C.sub.6 H.sub.5      CH.sub.2     ##STR267##      ##STR268##      --      ##STR269##      47/20/32/0/1.0  124 B-124 C.sub.6 H.sub.5      CH.sub.2     ##STR270##      ##STR271##      ##STR272##      ##STR273##      48.5/10/10/30/1.5  125 B-125 C.sub.6      H.sub.13     ##STR274##      ##STR275##      ##STR276##      ##STR277##      59/10.2/10/20/0.8  126 B-126 C.sub.6 H.sub.5      CH.sub.2     ##STR278##      --      ##STR279##      ##STR280##      80/0/16.3/2/5/1.2  127 B-127 C.sub.6      H.sub.13     ##STR281##      --      ##STR282##      ##STR283##      80/0/16/3/1.0  128 B-128 C.sub.6 H.sub.5      CH.sub.2     ##STR284##      ##STR285##      ##STR286##      ##STR287##      40/45/11/2.5/1.5  129 B-129 C.sub.3      H.sub.7     ##STR288##      ##STR289##      ##STR290##      ##STR291##      64/5/20/10/1.0  130 B-130 C.sub.8      H.sub.17     ##STR292##      ##STR293##      ##STR294##      ##STR295##      50/25/21/2.5/1.5

SYNTHESIS EXAMPLE 201 OF RESIN (B): Resin (B-201)

A mixed solution of 90 g of methyl acrylate, 10 g of acrylic acid and13.4 g of Initiator (I-201) shown below was heated to a temperature of40° C. under nitrogen gas stream. ##STR296##

The solution was irradiated with light from a high-pressure mercury lampof 400 W at a distance of 10 cm through a glass filter for 10 hours toconduct photopolymerization. The reaction mixture obtained wasreprecipitated in one liter of methanol, and the precipitates formedwere collected and dried to obtain 78 g of the polymer having a weightaverage molecular weight (Mw) of 2×10⁴.

A mixed solution of 10 g of the above described polymer, 65 g of methylmethacrylate, 25 g of methyl acrylate and 100 g of tetrahydrofuran washeated to a temperature of 50° C. under nitrogen gas stream andirradiated with light under the same condition as above for 15 hours.The reaction mixture was reprecipitated from 1.5 liters of methanol andthe precipitates thus formed were collected and dried to obtain 75 g ofthe polymer having an Mw of 8×10⁴. ##STR297##

SYNTHESIS EXAMPLE 202 OF RESIN (B): Resin (B-202)

A reaction procedure was conducted under the same condition as SynthesisExample 201 of Resin (B) except for using 14.8 g of Initiator (I-202)shown below in place of 13.4 g of Initiator (I-201) used in SynthesisExample 201 of Resin (B) to obtain 73 g of the polymer having an Mw of5×10⁴. ##STR298##

SYNTHESIS EXAMPLE 203 OF RESIN (B): Resin (B-203)

A mixed solution of 80 g of methyl methacrylate, 20 g of ethyl acrylate,13.5 g of Initiator (I-203) shown below and 150 g of tetrahydrofuran washeated at a temperature of 50° C. under nitrogen gas stream. ##STR299##

The mixture was irradiated with light under the same condition asdescribed in Synthesis Example 201 of Resin (B) for 10 hours. Thereaction mixture obtained was reprecipitated from one liter of methanoland the precipitates thus formed were collected and dried to obtain thepolymer.

A mixed solution of 60 g of the above described polymer, 30 g of methylacrylate, 10 g of methacrylic acid and 100 g of tetrahydrofuran washeated to a temperature of 50° C. under nitrogen gas stream andsubjected to light irradiation in the same manner as above for 10 hours.The reaction mixture obtained was reprecipitated from one liter ofmethanol, and the precipitates formed were collected and dried to obtain73 g of the polymer as a powder. A mixed solution of 60 g of the polymerthus obtained, 30 g of ethyl methacrylate, 10 g of methyl acrylate and100 g of tetrahydrofuran was heated to a temperature of 50° C. undernitrogen gas stream and subjected to light irradiation in the samemanner as above for 10 hours. The reaction mixture obtained wasreprecipitated from 1.5 liters of methanol and the precipitates formedwere collected and dried to obtain 76 g of the polymer having an Mw of9×10⁴ . ##STR300##

SYNTHESIS EXAMPLE 204 OF RESIN (B): Resin (B-204)

A mixed solution of 50 g of methyl methacrylate and 100 g oftetrahydrofuran was sufficiently degassed under nitrogen gas stream andcooled to -20° C. Then, 1.2 g of 1,1-diphenylpentyl lithium was added tothe mixture, and the reaction was conducted for 12 hours. Separately, amixed solution of 30 g of methyl acrylate, 3 g of triphenylmethylmethacrylate and 50 g of tetrahydrofuran was sufficiently degassed undernitrogen gas stream and the resulting mixed solution was added to theabove described mixture, and then reaction was further conducted for 8hours. Separately, a mixed solution of 50 g of methyl methacrylate and50 g of tetrahydrofuran was sufficiently degassed under nitrogen gasstream, and the resulting mixed solution was added to the abovedescribed mixture, and then reaction was further conducted for 10 hours.The temperature of the reaction mixture was adjusted to 0° C., 10 ml ofmethanol was added thereto, followed by reacting for 30 minutes, and thepolymerization reaction was terminated. The temperature of the polymersolution obtained was adjusted to 30° C. with stirring, 3 ml of anethanol solution of 30% hydrogen chloride was added thereto and themixture was stirred for one hour. Then, the solvent of the reactionmixture was distilled off under reduced pressure until the whole volumewas reduced to a half, and the mixture was reprecipitated from one literof methanol. The precipitates thus formed were collected and dried underreduced pressure to obtain 65 g of the polymer having an Mw of 8.5×10⁴.##STR301##

SYNTHESIS EXAMPLE 205 OF RESIN (B): Resin (B-205)

A mixed solution of 70 g of methyl methacrylate, 30 g of methylacrylate, 0.5 g of (tetraphenyl porphinato) aluminum methyl and 200 g ofmethylene chloride was raised to a temperature of 30° C. under nitrogengas stream. The mixture was irradiated with light from a xenon lamp of300 W at a distance of 25 cm through a glass filter, and the reactionwas conducted for 12 hours. To the mixture were further added 40 g ofethyl acrylate and 6.4 g of benzyl methacrylate, followed by reactingfor 10 hours with light irradiation in the same manner as above.Further, 70 g methyl methacrylate and 30 g of methyl acrylate were addedto the mixture, followed by reacting for 12 hours with light irradiationin the same manner as above. Then, 3 g of methanol was added to thereaction mixture, followed by stirring for 30 minutes, and the reactionwas terminated. Then, Pd-C was added to the reaction mixture, and acatalytic reduction reaction was conducted for one hour at a temperatureof 25° C. After removing the insoluble substances from the reactionmixture by filtration, the reaction mixture was reprecipitated from 2liters of methanol, and the precipitates thus formed were collected byfiltration and dried to obtain 180 g of the polymer having an Mw of8.5×10⁴. ##STR302##

SYNTHESIS EXAMPLES 206 TO 215 OF RESIN (B): Resins (B-206) to (B-215)

Each of the resins (B) shown in Table 13 below was synthesized in thesame reaction procedure as described in Synthesis Example 202 of Resin(B). The Mw of each of the polymers obtained was in a range of from5×10⁴ to 7×10⁴.

    TABLE 13      ##STR303##       Synthesis        Examples of       p/q/r/y/z Resin (B) Resin (B)     R.sub.1 X.sub.1 R.sub.2 Y.sub.2 Z.sub.3 (weight ratio)               206 B-206 CH.sub.3 -- CH.sub.3 --      ##STR304##      32.5/0/32/0/3  207 B-207 CH.sub.3 -- C.sub.2      H.sub.5 --     ##STR305##      36/0/25/0/3      208 B-208 CH.sub.3     ##STR306##      CH.sub.3      ##STR307##      ##STR308##      33/5/20/3/1  209 B-209 C.sub.2      H.sub.5     ##STR309##      CH.sub.3 --      ##STR310##      37.1/5/15/0/0.8  210 B-210 C.sub.3      H.sub.7     ##STR311##      CH.sub.3      ##STR312##      ##STR313##      30.5/5/20/8/1.0      211 B-211 CH.sub.3     ##STR314##      CH.sub.3      ##STR315##      ##STR316##      30/5/19/10/1.0      212 B-212 CH.sub.3     ##STR317##      C.sub.2      H.sub.5 --     ##STR318##      40.5/0/15/0/4  213 B-213 C.sub.6      H.sub.5     ##STR319##      CH.sub.3      ##STR320##      ##STR321##      15/10/45/3/2  214 B-214 CH.sub.2 C.sub.6      H.sub.5 -- CH.sub.3     ##STR322##      ##STR323##      37.5/0/15/6.5/3.5  215 B-215 C.sub.6      H.sub.5     ##STR324##      C.sub.2      H.sub.5     ##STR325##      ##STR326##      40/0/14/4/2

SYNTHESIS EXAMPLES 216 TO 219 OF RESIN (B): Resins (B-216) to (B-219)

Each of the polymers shown in Table 14 below was synthesized in the sameprocedure as described in Synthesis Example 201 of Resin (B) except forusing 5×10⁻² moles of each of the initiators shown in Table 14 below inplace of 13.4 g of Initiator (I-201) used in Synthesis Examples 201 ofResin (B). The Mw of each of the polymers was in a range of from 7×10⁴to 8.5×10⁴.

                                      TABLE 14                                    __________________________________________________________________________    Synthesis                                                                     Examples of                                                                   Resin (B)                                                                            Resin (B)                                                                          Initiator                                                         __________________________________________________________________________    216    B-216                                                                               ##STR327##                   I-204                               217    B-217                                                                               ##STR328##                   I-205                               218    B-218                                                                               ##STR329##                   I-206                               219    B-219                                                                               ##STR330##                   I-207                               __________________________________________________________________________

SYNTHESIS EXAMPLES 220 TO 226 OF RESIN (B): Resins (B-220) to (B-226)

A mixed solution of 90 g of benzyl methacrylate, 10 g of acrylic acidand 7.8 g of Initiator (1-208 ) shown below was heated to a temperatureof 40° C. under nitrogen gas stream. ##STR331##

The mixture was reacted under the same light-irradiation condition asdescribed in Synthesis Example 201 of Resin (B) for 5 hours. The polymerobtained was dissolved in 200 g of tetrahydrofuran, reprecipitated from1.0 liter of methanol, and the precipitates formed were collected byfiltration and dried.

A mixed solution of 20 g of the polymer thus obtained, a monomercorresponding to each of the polymer components shown in Table 15 belowand 100 g of tetrahydrofuran was reacted with light irradiation in thesame manner as above for 15 hours. The polymer obtained wasreprecipitated from 1.5 liters of methanol and the precipitates formedwere collected by filtration and dried. The yield of each polymer was ina range of from 60 to 70 g and the Mw thereof was in a range of from4×10⁴ to 7×10⁴.

                                      TABLE 15                                    __________________________________________________________________________     ##STR332##                                                                   Synthesis                                    x/y/z                            Example of                                                                    Resin (B)                                                                            Resin (B)                                                                          R      Y             Z           (weight ratio)                   __________________________________________________________________________    220    B-220                                                                              CH.sub.3                                                                             --            --          40/0/0                           221    B-221                                                                              C.sub.2 H.sub.5                                                                       ##STR333##   --          38/2/0                           222    B-222                                                                               CH.sub.3                                                                             ##STR334##                                                                                  ##STR335## 27/12/1                          223    B-223                                                                              CH.sub.3                                                                              ##STR336##   --          37/3/0                           224    B-224                                                                              CH.sub.2 C.sub.6 H.sub.5                                                              ##STR337##   --          38.5/1.5/0                       225    B-225                                                                              C.sub.2 H.sub.5                                                                      --            --          40/0/0                           226    B-226                                                                              C.sub.2 H.sub.5                                                                       ##STR338##                                                                                  ##STR339## 30/7.5/2.5                       __________________________________________________________________________

EXAMPLE I-1

A mixture of 6 g (solid basis) of Resin (A-7), 34 g (solid basis) ofResin (B-1), 200 g of photoconductive zinc oxide, 0.018 g of Cyanine Dye(I-1) shown below, 0.15 g of phthalic anhydride and 300 g of toluene wasdispersed by a homogenizer (manufactured by Nippon Seiki K.K.) at arotation of 6×10³ r.p.m. for 10 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 22 g/m², followed by drying at 110° C.for 10 seconds. The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH (relative humidity) for 24 hours to preparean electrophotographic light-sensitive material. ##STR340##

COMPARATIVE EXAMPLE I-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example I-1, except for using 34 g of Resin (R-I-l) shownbelow in place of 34 g of Resin (B-1) used in Example I-1. ##STR341##

COMPARATIVE EXAMPLE I-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example I-1, except for using 34 g of Resin (R-I-2) shownbelow in place of 34 g of Resin (B-1) used in Example I-1. ##STR342##

With each of the light-sensitive material thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table I-1 below.

                  TABLE I-1                                                       ______________________________________                                                           Comparative                                                                              Comparative                                               Example I-1                                                                            Example I-1                                                                              Example I-2                                     ______________________________________                                        Electrostatic                                                                 Characteristics*.sup.1)                                                       V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                 650        650        655                                         II (30° C., 80% RH)                                                                640        640        640                                         D.R.R.                                                                        (90 sec value) (%)                                                            I (20° C., 65% RH)                                                                 88         85         86                                          II (30° C., 80% RH)                                                                86         80         82                                          E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                 12         22         18                                          II (30° C., 80% RH)                                                                15         28         23                                          E.sub.1/100 (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                 18         37         29                                          II (30° C., 80% RH)                                                                23         48         37                                          Image Forming                                                                 Performance*.sup.2)                                                           I (20° C., 65% RH)                                                                 Very       Scratches of                                                                             Scratches of                                            good       fine lines and                                                                           fine lines and                                                     letters,   letters,                                                           unevenness in                                                                            unevenness in                                                      half tone area                                                                           half tone area                              II (30° C., 80% RH)                                                                Very       Scratches of                                                                             Scratches of                                            good       fine lines and                                                                           fine lines and                                                     letters,   letters,                                                           unevenness in                                                                            unevenness in                                                      half tone area                                                                           half tone area                              ______________________________________                                    

The evaluation of each item shown in Table I-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of phot6conductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (Condition I) or 30° C. and 80% RH (Condition II).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ("ELP-T" produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent("Isopar G" manufactured by Esso Chemical K. K.) and fixed. Theduplicated image obtained was visually evaluated for fog and imagequality. The ambient condition at. the time of image formation was 20°C. and 65% RH (Condition I) or 30° C. and 80% RH (Condition II).

As can be seen from the results shown in Table I-1, the light-sensitivematerial according to the present invention had good electrostaticcharacteristics. The duplicated image obtained thereon was clear andfree from background fog. On the contrary, with the light-sensitivematerials of Comparative Examples I-1 and I-2 the decrease inphotosensitivity (E_(1/10) and E1/100) occurred, and in the duplicatedimages the scratches of fine lines and letters were observed and aslight background fog remained without removing after the rinsetreatment. Further, the occurrence of unevenness in half tone areas ofcontinuous gradation of the original was observed regardless of theelectrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller this value, the less the background fog in the non-imageareas.

More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying both therequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlyusing the binder resin according to the present invention.

EXAMPLE I-2

A mixture of 5 g (solid basis) of Resin (A-3), 35 g (solid basis) ofResin (B-2), 200 g of photoconductive zinc oxide, 0.020 g of Methine Dye(I-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g of toluenewas treated in the same manner as described in Example I-1 to prepare anelectrophotographic light-sensitive material. ##STR343##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table I-2below.

                  TABLE I-2                                                       ______________________________________                                                              Example I-2                                             ______________________________________                                        Smoothness of Photoconductive Layer*.sup.3)                                                           650                                                   (sec/cc)                                                                      Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                              I (20° C., 65% RH)                                                                    660                                                            II (30° C., 80% RH)                                                                   650                                               D.R.R.       I (20° C., 65% RH)                                                                    88                                                (90 sec value) (%)                                                                         II (30° C., 80% RH)                                                                   85                                                E.sub.1/10 (erg/cm.sup.2)                                                                  I (20° C., 65% RH)                                                                    15                                                             II (30° C., 80% RH)                                                                   17                                                E.sub.1/100 (erg/cm.sup.2)                                                                 I (20° C., 65% RH)                                                                    23                                                             II (30° C., 80% RH)                                                                   26                                                Image Forming Performance                                                                I (20° C., 65% RH)                                                                  Very good                                                        II (30° C., 80% RH)                                                                 Very good                                             Contact Angle with Water*.sup.4) (°)                                                           10 or less                                            Printing Durability*.sup.5)                                                                           10,000 prints                                         ______________________________________                                    

The evaluation of each item shown in Table I-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*4) Contact Anqle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ("ELP-EX" produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*5) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *4) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52", manufactured by Sakurai Seisakusho K. K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table I-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic, as shown by a small contact angle of10.sup.° or less with water. On practical printing using the resultingmaster plate, 10,000 prints of clear image without background stainswere obtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES I-3 TO I-18

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example I-2, except for using each of Resins(A) and Resins (B) shown in Table I-3 below in place of Resin (A-3) andResin (B-2) used in Example I-2, respectively.

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in Example I-2.The results obtained are shown in Table I-3 below.

                  TABLE I-3                                                       ______________________________________                                                                                   E.sub.1/100                               Resin   Resin   V.sub.10                                                                            D.R.R.                                                                              E.sub.1/10                                                                            (erg/                              Example                                                                              (A)     (B)     (-V)  (%)   (erg/cm.sup.2)                                                                        cm.sup.2)                          ______________________________________                                        I-3    A-1     B-5     600   80    20      31                                 I-4    A-4     B-6     605   81    20      32                                 I-5    A-5     B-7     605   81    21      31                                 I-6    A-6     B-8     610   81    19      29                                 I-7    A-8     B-9     680   85    15      28                                 I-8    A-12    B-10    605   81    20      30                                 I-9    A-14    B-11    580   80    23      35                                 I-10   A-17    B-12    650   83    18      30                                 I-11   A-18    B-13    660   83    17      29                                 I-12   A-19    B-14    630   82    19      31                                 I-13   A-23    B-16    660   84    16      28                                 I-14   A-24    B-17    580   80    19      32                                 I-15   A-25    B-19    570   79    22      35                                 I-16   A-27    B-20    585   80    20      31                                 I-17   A-28    B-21    580   79    23      34                                 I-18   A-29    B-22    690   84    16      29                                 ______________________________________                                    

The electrostatic characteristics were evaluated under condition of 30°C. and 80% RH.

As a result of the evaluation on image forming performance of eachlight-sensitive material, it was found that clear duplicated imageshaving good reproducibility of fine lines and letters and no occurrenceof unevenness in half tone areas without the formation of background fogwere obtained.

EXAMPLES I-19 TO I-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example I-1, except for using each of thedye shown in Table I-4 below in place of Cyanine Dye (I-1) used inExample I-1.

                                      TABLE I-4                                   __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    I-19 (I-III)                                                                              ##STR344##                                                        I-20 (I-IV)                                                                               ##STR345##                                                        I-21 (I-V)                                                                                ##STR346##                                                        I-22 (I-VI)                                                                               ##STR347##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RE).

EXAMPLES I-23 AND I-24

A mixture of 6.5 g of Resin (A-1) (Example I-23) or Resin (A-29)(Example 1-24), 33.5 g of Resin (B-9), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (I-VII) shown below, 0.03 g of MethineDye (I-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at 7×10³ r.p.m. for 10 minutes toprepare a coating composition for a light-sensitive layer. The coatingcomposition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 20g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR348##

COMPARATIVE EXAMPLE I-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example I-23, except for using Resin (R-I-3) shown below inplace of Resin (B-9) used in Example I-23. ##STR349##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example I-2. Theresults obtained are shown in Table I-5 below.

                                      TABLE I-5                                   __________________________________________________________________________                       Example I-23                                                                         Example I-24                                                                         Comparative Example I-3                      __________________________________________________________________________    Binder Resin       (A-1)/(B-9)                                                                          (A-29)/(B-9)                                                                         (A-1)/(R-I-3)                                Smoothness of Photoconductive                                                                    550    560    560                                          Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.6)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                               595    685    580                                                   II (30° C., 80% RH)                                                              585    675    570                                          D.R.R. (%)                                                                             I (20° C., 65% RH)                                                               93     96     92                                                    II (30° C., 80% RH)                                                              90     94     90                                           E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                               6.3    5.8    7.5                                                   II (30° C., 80% RH)                                                              7.0    6.3    8.0                                          E.sub.1/100 (lux/sec)                                                                  I (20° C., 65% RH)                                                               10.0   9.0    13.0                                                  II (30° C., 80% RH)                                                              11.2   9.5    14.0                                         Image Forming*.sup.7)                                                                  I (20° C., 65% RH)                                                               Good   Very good                                                                            Edge mark of cutting                         Performance                                                                            II (30° C., 80% RH)                                                              Good   Very good                                                                            Edge mark of cutting,                                                         unevenness in half                                                            tone area                                    Contact Angle with Water                                                                         10 or less                                                                           10 or less                                                                           10 or less                                   Printing Durability                                                                              10,000 10,000 Background stain due to                                         prints prints edge mark of cutting                                                          occurred from the start                                                       of printing                                  __________________________________________________________________________

The characteristics were evaluated in the same manner as in Example I-2,except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*6) Measurement of Electrostatic Characteristics:E_(1/10) and E_(1/100)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux.sec) was calculatedtherefrom.

*7) Image Forminq Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost the same properties with respect to thesurface smoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example I-3 had the particularly large value ofphotosensitivity E_(1/100), and this tendency increased under the hightemperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive material accordingto the present invention were good. Further, those of Example 1-24 usingthe resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example I-3. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example I-3,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention were excellent in allaspects of the surface smoothness and mechanical strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, it can be seen that the electrostatic characteristicsare more improved by using the resin (A').

EXAMPLE I-25

A mixture of 5 g of Resin (A-23), 35 g of Resin (B-12), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example I-23 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example I-23, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH). Further, when the material was employed as an offset master plateprecursor, 10,000 prints of clear image were obtained.

EXAMPLES I-26 TO I-37

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example I-25, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table I-6 below inplace of 5 g of Resin (A-23) and 35 g of Resin (B-12) used in ExampleI-25, respectively.

                  TABLE I-6                                                       ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        I-26          A-1           B-1                                               I-27          A-2           B-2                                               I-28          A-4           B-3                                               I-29          A-5           B-4                                               I-30          A-9           B-6                                               I-31          A-15          B-15                                              I-32          A-20          B-18                                              I-33          A-21          B-20                                              I-34          A-22          B-21                                              I-35          A-25          B-22                                              I-36          A-26          B-23                                              I-37          A-28          B-13                                              ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionof .high temperature and high humidity (30° C. and 80% RH). Further,when these materials were employed as offset master plate precursors,more than 10,000 prints of a clear image free from background stainswere obtained respectively.

EXAMPLE II-1

A mixture of 6 g (solid basis) of Resin (A-104), 34 g (solid basis) ofResin (B-i), 200 g of photoconductive zinc oxide, 0.018 g of Cyanine Dye(II-1) shown below, 0.45 g of phthalic anhydride and 300 g of toluenewas dispersed by a homogenizer (manufactured by Nippon Seiki K. K.) at arotation of 7×10³ r.p.m. for 10 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 25 g/m², followed by drying at 110° C.for 10 seconds. The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR350##

COMPARATIVE EXAMPLE II-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-1, except for using 34 g of Resin (R-II-1) shownbelow in place of 34 g of Resin (B-b 1) used in Example II-1. ##STR351##

COMPARATIVE EXAMPLE II-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-1, except for using 34 g of Resin (R-II-2) shownbelow in place of 34 g of Resin (B-1) used in Example II-1. ##STR352##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table II-1 below.

                                      TABLE II-1                                  __________________________________________________________________________                          Comparative                                                                            Comparative                                                  Example II-1                                                                          Example II-1                                                                           Example II-2                                   __________________________________________________________________________    Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                   680     660      670                                            II (30° C., 80% RH)                                                                  660     635      645                                            III (15° C., 30% RH)                                                                 690     665      680                                            D.R.R. (90 sec value) (%)                                                     I (20° C., 65% RH)                                                                   89      85       87                                             II (30° C., 80% RH)                                                                  84      80       83                                             III (15° C., 30% RH)                                                                 89      87       89                                             E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                   15.5    22       20                                             II (30° C., 80% RH)                                                                  18      28       25                                             III (15° C., 30% RH)                                                                 24      30       28                                             Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                   Very good                                                                             Good     Good                                           II (30° C., 80% RH)                                                                  Good    Unevenness                                                                             Unevenness                                                           in half tone                                                                           in half tone                                                         area, slight                                                                           area, slight                                                         background fog                                                                         background fog                                 III (15° C., 30% RH)                                                                 Good    White spots                                                                            White spots                                                          in image in image                                                             portion  portion                                        __________________________________________________________________________

The evaluation of each item shown in Table II-1 was conducted in thefollowing manner.

*1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. The measurements were conducted under ambientcondition of 20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and30% RH

*2) Image Forminq Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of iso-paraffinic solventIsopar G (manufactured by Esso Chemical K. K.) and fixed. The duplicatedimage obtained was visually evaluated for fog and image quality. Theambient condition at the time of image formation was 20° C. and 65% RH(I), 30° C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table II-1, the light-sensitivematerial according to the present invention exhibited good electrostaticcharacteristics and provided duplicated image which was clear and freefrom background fog, even when the ambient condition was fluctuated. Onthe contrary, while the light-sensitive materials of ComparativeExamples II-1 and II-2 exhibited good image forming performance underthe ambient condition of normal temperature and normal humidity (I), theoccurrence of unevenness of density was observed in the highly accurateimage portions, in particular, half tone areas of continuous gradationunder the ambient condition of high temperature and high humidity (II)regardless of the electrostatic characteristics. Also, a slightbackground fog remained without removing after the rinse treatment.Further, the occurrence of unevenness of small white spots at random inthe image portion was observed under the ambient condition of lowtemperature and low humidity (III)

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance (in particular, for highly accurate image) and beingadvantageously employed particularly in a scanning exposure system usinga semiconductor laser beam can be obtained only when the binder resinaccording to the present invention is used.

EXAMPLE II-2

A mixture of 5 g (solid basis) of Resin (A-119), 35 g (solid basis) ofResin (B-2), 200 g of photoconductive zinc oxide, 0,020 g of Methine Dye(II-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g of toluenewas treated in the same manner as described in Example II-1 to preparean electrophotographic light-sensitive material. ##STR353##

COMPARATIVE EXAMPLE II-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-2, except for using 35 g of Resin (R-II-3) shownbelow in place of 35 g of Resin (B-2) used in Example II-2. ##STR354##

COMPARATIVE EXAMPLE II-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-2, except for using 35 g of Resin (R-II-4) shownbelow in place of 35 g of Resin (B-2) used in Example II-2. ##STR355##

With each of the light-sensitive materials thus-prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table II-2 below.

                                      TABLE II-2                                  __________________________________________________________________________                                Comparative                                                                           Comparative                                                   Example II-2                                                                          Example II-3                                                                          Example II-4                              __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                             430     440     415                                       Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                    96      80      85                                        Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                                730     700     720                                                II (30° C., 80% RH)                                                               700     675     695                                                III (15° C., 30% RH)                                                              740     705     725                                       D.R.R. (%)                                                                             I (20° C., 65% RH)                                                                88      83      85                                        (90 sec value)                                                                         II (30° C., 80% RH)                                                               84      79      81                                                 III (15° C., 30% RH)                                                              89      85      86                                        E.sub.1/10 (erg/cm.sup.2)                                                              I (20° C., 65% RH)                                                                15.1    22      20                                                 II (30° C., 80% RH)                                                               14.8    19.4    18.6                                               III(15° C., 30% RH)                                                               18.5    28      24                                        Image Forming                                                                          I (20° C., 65% RH)                                                                Good    Good    Good                                      Performance                                                                            II (30° C., 80% RH)                                                               Good    Unevenness in                                                                         Slight unevenness                                                     half tone area                                                                        in half tone area                                  III (15° C., 30% RH)                                                              Good    Unevenness in                                                                         Unevenness in                                                         half tone area,                                                                       half tone area,                                                       unevenness of                                                                         unevenness of                                                         white spots in                                                                        white spots in                                                        image portion                                                                         image portion                             Water Retentivity of*.sup.5)                                                                      No background                                                                         Background                                                                            Slight background                         Light-Sensitive Material                                                                          stain at all                                                                          stain   stain                                     Printing Durability*.sup.6)                                                                       10,000 prints                                                                         4,000 prints                                                                          6,000 prints                              __________________________________________________________________________

The evaluation of each item shown in Table II-2 was conducted in thefollowing manner.

*3) smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine manufactured by Shinto Kagaku K. K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ELP-EX (produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model " manufactured by Hamada Printing MachineManufacturing Co.) and printing was conducted using distilled water asdampening water. The extent of background stain occurred on the 50thprint was visually evaluated. This testing method corresponds toevaluation of water retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52",manufactured by Sakurai SeisakushoK. K.), and printing was carried out on paper. The number of printsobtained until background stains in the non-image areas appeared or thequality of the image areas was deteriorated was taken as the printingdurability. The larger the number of the prints, the higher the printingdurability.

As can be seen from the results shown in Table II-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic and adhesion of ink was not observed atall as a result of the evaluation of water retentivity under the forcedcondition. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples II-3 and II-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most 5,000 to 6,000prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES II-3 TO II-18

Each electrophotographic right-sensitive material was prepared in thesame manner as described in Example II-2, except for using each ofResins (A) and Resins (B) shown in Table II-3 below in place of Resin(A-119) and Resin (B-2) used in Example II-2, respectively.

                  TABLE II-3                                                      ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        II-3          A-105         B-3                                               II-4          A-106         B-4                                               II-5          A-108         B-5                                               II-6          A-109         B-6                                               II-7          A-110         B-7                                               II-8          A-111         B-8                                               II-9          A-112         B-9                                               II-10         A-116         B-10                                              II-11         A-121         B-11                                              II-12         A-122         B-12                                              II-13         A-123         B-13                                              II-14         A-128         B-14                                              II-15         A-129         B-15                                              II-16         A-131         B-17                                              II-17         A-132         B-19                                              II-18         A-133         B-23                                              ______________________________________                                    

The electrostatic characteristics and image forming performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example II-1. Each light-sensitive material exhibited goodelectrostatic characteristics. As a result of the evaluation on imageforming performance of each light-sensitive material, it was found thatclear duplicated images having good reproducibility of fine lines andletters and no occurrence of unevenness in half tone areas without theformation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example II-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES II-19 TO II-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example II-1, except for using each of thedye shown in Table II-4 below in place of Cyanine Dye (II-1) used inExample II-1.

                                      TABLE II-4                                  __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    II-19                                                                              (II-III)                                                                             ##STR356##                                                        II-20                                                                              (II-IV)                                                                              ##STR357##                                                        II-21                                                                              (II-V)                                                                               ##STR358##                                                        II-22                                                                              (II-VI)                                                                              ##STR359##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES II-23 AND II-24

A mixture of 6.5 g of Resin (A-101) (Example II-23) or Resin (A-104)(Example II-24), 33.5 g of Resin (B-9), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (II-VII) shown below, 0.03 g of MethineDye (II-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a h mogenizer at a rotation of 7×10³ r.p.m. for10 minutes to prepare a coating composition for a light-sensitive layer.The coating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coyerage of 25g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR360##

COMPARATIVE EXAMPLE II-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example II-23, except for using 33.5 g of Resin (R-II-5)shown below in place of 33.5 g of Resin (B-9) used in Example II-23.##STR361##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example II-2.The results obtained are shown in Table II-5 below.

                                      TABLE II-5                                  __________________________________________________________________________                        Example II-23                                                                         Example II-24                                                                         Comparative Example                       __________________________________________________________________________                                        II-5                                      Binder Resin        (A-101)/(B-9)                                                                         (A-104)/(B-9)                                                                         (A-101)/(R-II-5)                          Smoothness of Photoconductive                                                                     400     410     400                                       Layer (sec/cc)                                                                Mechanical Strength of                                                                            95      96      86                                        Photoconductive Layer (%)                                                     Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                                605     700     600                                                II (30° C., 80% RH)                                                               580     680     575                                                III (15° C., 30% RH)                                                              620     730     625                                       D.R.R. (%)                                                                             I (20° C., 65% RH)                                                                95      97      93                                                 II (30° C., 80% RH)                                                               93      94      91                                                 III (15° C., 30% RH)                                                              96      96      92                                        E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                                11.6    73      13.7                                               II (30° C., 80% RH)                                                               11.0    8.4     13.3                                               III (15° C., 30% RH)                                                              12.3    9.6     14.2                                      Image Forming*.sup.8)                                                                  I (20° C., 65% RH)                                                                Good    Very good                                                                             Good                                      Performance                                                                            II (30° C., 80% RH)                                                               Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                          III (15° C., 30% RH)                                                              Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in image                                                           portion                                   Water Retentivity of                                                                              Good    Good    Slight background stain                   Light-Sensitive Material                                                      Printing Durability 10,000  10,000  Background stain from                                         prints  prints  the start of printing                     __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleII-2, except that same electro-static characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/1) Q

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 thereof was determined, and the exposure amountE_(1/10) (lux.sec) was calculated therefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example II-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example II-24 using the resin (A') werevery good. The value of E_(1/100) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example II-5. Also, theoccurrence of unevenness in half tone area of continuous gradation andunevenness of small white spots in image portion was observed on theduplicated image when the ambient conditions at the time of the imageformation were high temperature and high humidity (II) and lowtemperature and low humidity (III).

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the plate printing was conducted. The plates according to thepresent invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example II-5,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that only thelight-sensitive materials according to the present invention can provideexcellent performance.

EXAMPLE II-25

A mixture of 5 g of Resin (A-122), 35 g of Resin (B-22), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bremophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example II-24 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example II-24, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor forprinting, 10,000 prints of clear image were obtained.

EXAMPLES II-26 TO II-49

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example II-25, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table II-6 below inplace of 5 g of Resin (A-122) and 35 g of Resin (B-22) used in ExampleII-25, respectively.

                  TABLE II-6                                                      ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        II-26         A-102         B-6                                               II-27         A-103         B-8                                               II-28         A-104         B-11                                              II-29         A-106         B-13                                              II-30         A-107         B-16                                              II-31         A-110         B-18                                              II-32         A-112         B-19                                              II-33         A-113         B-20                                              II-34         A-114         B-21                                              II-35         A-115         B-22                                              II-36         A-116         B-23                                              II-37         A-117         B-17                                              II-38         A-123         B-2                                               II-39         A-129         B-5                                               II-40         A-130         B-14                                              II-41         A-131         B-17                                              II-42         A-132         B-16                                              II-43         A-133         B-1                                               II-44         A-124         B-3                                               II-45         A-121         B-21                                              II-46         A-119         B-22                                              II-47         A-106         B-23                                              II-48         A-105         B-15                                              II-49         A-104         B-12                                              ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

EXAMPLE III-1

A mixture of 6 g (solid basis) of Resin (A-205), 34 g (solid basis) ofResin (B-1), 200 g of photoconductive zinc oxide, 0.018 g of Cyanine Dye(III-I) shown below, 0.15 g of phthalic anhydride and 300 g of toluenewas dispersed by a h mogenizer manufactured by Nippon Seiki K. K.) at arotation of 6×10³ r.p.m. for 10 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 22 g/m², followed by drying at 110° C.for 10 seconds. The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH (relative humidity) for 24 hours to preparean electrophotographic light-sensitive material. ##STR362##

COMPARATIVE EXAMPLE III-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-1, except for using 34 g of Resin (R-III-1)shown below in place of 34 g of Resin (B-1) used in Example III-1.##STR363##

COMPARATIVE EXAMPLE III-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-1, except for using 34 g of Resin (R-III-2)shown below in place of 34 g of Resin (B-1) used in Example III-1.##STR364##

With each of the light-sensitive material thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table III-1 below.

                                      TABLE III-1                                 __________________________________________________________________________                          Comparative                                                                            Comparative                                                  Example III-1                                                                         Example III-1                                                                          Example III-2                                  __________________________________________________________________________    Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                   730     700      720                                            II (30° C., 80% RH)                                                                  710     670      705                                            III (15° C., 30% RH)                                                                 740     720      730                                            D.R.R. (90 sec value) (%)                                                     I (20° C., 65% RH)                                                                   88      88       88                                             II (30° C., 80% RH)                                                                  85      80       83                                             III (15° C., 30% RH)                                                                 88      88       89                                             E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                   16.0    20       18                                             II (30° C., 80% RH)                                                                  14.0    18       16                                             III (15° C., 30% RH)                                                                 19.0    28       24                                             Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                   Very good                                                                             Good     Good                                           II (30° C., 80% RH)                                                                  Good    Unevenness                                                                             Unevenness                                                           in half tone                                                                           in half tone                                                         area, slight                                                                           area, slight                                                         background fog                                                                         background fog                                 III (15° C., 30% RH)                                                                 Good    White spots                                                                            White spots                                                          in image in image                                                             portion  portion                                        __________________________________________________________________________

The evaluation of each item shown in Table III-1 was conducted inthe-following manner.

1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP- 428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. The measurements were conducted under ambientcondition of 20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and30% RH (III).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent IsoparG manufactured by Esso Chemical K. K.) and fixed. The duplicated imageobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table III-1, thelight-sensitive material according to the present invention exhibitedgood electrostatic characteristics and provided duplicated image whichwas clear and free from background fog, even when the ambient conditionwas fluctuated. On the contrary, while the light-sensitive materials ofComparative Examples III-1 and III-2 exhibited good image formingperformance under the ambient condition of normal temperature and normalhumidity (I), the occurrence of unevenness of density was observed inthe highly accurate image portions, in particular, half tone areas ofcontinuous gradation under the ambient condition of high temperature andhigh humidity (II) regardless of the electrostatic characteristics.Also, a slight background fog remained unremoved after the rinsetreatment. Further, the occurrence of unevenness of small white spots atrandom in the image portion was observed under the ambient condition oflow temperature and low humidity (III).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance (in particular, for highly accurate image) and beingadvantageously employed particularly in a scanning exposure system usinga semiconductor laser beam can be obtained only when the binder resinaccording to the present invention is used.

EXAMPLE III-2

A mixture of 5 g (solid basis) of Resin (A-221), 35 g (solid basis) ofResin (B-2), 200 g of photoconductive zinc oxide, 0.020 g of Methine Dye(III-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example III-1 toprepare an electrophotographic light-sensitive material. ##STR365##

COMPARATIVE EXAMPLE III-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-2, except for using 35 g of Resin (R-III-3)shown below in place of 35 g of Resin (B-2) used in Example III-2.##STR366##

COMPARATIVE EXAMPLE III-4

An electrophbtographic light-sensitive material was prepared in the samemanner as in Example III-2, except for using 35 g of Resin (R-III-4)shown below in place of 35 g of Resin (B-2) used in Example III-2.##STR367##

With each of the light-sensitive materials thus prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table III-2 below.

                                      TABLE III-2                                 __________________________________________________________________________                                Comparative                                                                            Comparative                                                  Example III-2                                                                         Example III-3                                                                          Example III-4                            __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                             400     410      405                                      Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                    95      80       86                                       Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                                680     660      675                                               II (30° C., 80% RH)                                                               665     640      660                                               III (15° C., 30% RH)                                                              690     675      685                                      D.R.R. (%)                                                                             I (20° C., 65% RH)                                                                88      83       88                                       (90 sec value)                                                                         II (30° C., 80% RH)                                                               84      78       81                                                III (15° C., 30% RH)                                                              89      85       88                                       E.sub.1/10 (erg/cm.sup.2)                                                              I (20° C., 65% RH)                                                                16.0    20       20                                                II (30° C., 80% RH)                                                               15.0    17       18                                                III (15° C., 30% RH)                                                              19.2    29       24                                       Image Forming                                                                          I (20° C., 65% RH)                                                                Good    Good     Good                                     Performance                                                                            II (30° C., 80% RH)                                                               Good    Unevenness in                                                                          Slight unevenness                                                    half tone area                                                                         in half tone area                                 III (15° C., 30% RH)                                                              Good    Unevenness in                                                                          Unevenness in                                                        half tone area,                                                                        half tone area,                                                      unevenness of                                                                          unevenness of                                                        white spots in                                                                         white spots in                                                       image portion                                                                          image portion                            Water Retentivity of*.sup.5)                                                                      No background                                                                         Background                                                                             Slight background                        Light-Sensitive Material                                                                          stain at all                                                                          stain    stain                                    Printing Durability*.sup.6)                                                                       10,000 prints                                                                         4,500 prints                                                                           6,000 prints                             __________________________________________________________________________

The evaluation of each item shown in Table III-2 was conducted in thefollowing manner.

*3) smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine manufactured by Shinto Kagaku K. K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ELP-EX (produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model " manufactured by Hamada Printing MachineManufacturing Co.) and printing was conducted using distilled water asdampening water. The extent of background stain occurred on the 50thprint was visually evaluated. This testing method corresponds toevaluation of water retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52",manufactured by Sakurai SeisakushoK. K.) for printing. The number of prints obtained until backgroundstains in the non-image areas appeared or the quality of the image areaswas deteriorated was taken as the printing durability. The larger thenumber of the prints, the higher the printing durability.

As shown in Table III-2, the light-sensitive material according to thepresent invention had good surface smoothness, film strength andelectrostatic characteristics of the photoconductive layer. Theduplicated image obtained was clear and free from background fog in thenon-image area. These results appear to be due to sufficient adsorptionof the binder resin onto the photoconductive substance and sufficientcovering of the surface of the particles with the binder resin. For thesame reason, when it was used as an offset master plate precursor,oil-desensitization of the offset master plate precursor with anoil-desensitizing solution was sufficient to render the non-image areassatisfactorily hydrophilic and adhesion of ink was not observed at allas a result of the evaluation of water retentivity under the forcedcondition. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples III-3 and III-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most 4,000 to 6,000prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES III-3 TO III-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example III-2, except for using each ofResins (A) and Resins (B) shown in Table III-3 below in place of Resin(A-221) and Resin (B-2) used in Example III-2, respectively.

                  TABLE III-3                                                     ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        III-3         A-203         B-1                                               III-4         A-204         B-3                                               III-5         A-206         B-4                                               III-6         A-207         B-5                                               III-7         A-208         B-7                                               III-8         A-209         B-9                                               III-9         A-210         B-10                                              III-10        A-211         B-11                                              III-11        A-213         B-12                                              III-12        A-214         B-13                                              III-13        A-215         B-14                                              III-14        A-216         B-15                                              III-15        A-218         B-16                                              III-16        A-221         B-17                                              III-17        A-222         B-18                                              III-18        A-223         B-19                                              III-19        A-214         B-20                                              III-20        A-212         B-21                                              III-21        A-210         B-22                                              III-22        A-207         B-23                                              ______________________________________                                    

The electrostatic characteristics and image forming performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example III-1. Each light-sensitive material exhibited goodelectrostatic characteristics. As a result of the evaluation on imageforming performance of each light-sensitive material, it was found thatclear duplicated images having good reproducibility of fine lines andletters and no occurrence of unevenness in half tone areas without theformation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example III-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES III-23 TO III-26

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example III-1, except for using each of thedye shown in Table III-4 below in place of Cyanine Dye (III-I) used inExample III-1.

                                      TABLE III-4                                 __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    III-23                                                                             (III-III)                                                                            ##STR368##                                                        III-24                                                                             (III-IV)                                                                             ##STR369##                                                        III-25                                                                             (III-V)                                                                              ##STR370##                                                        III-26                                                                             (III-VI)                                                                             ##STR371##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES III-27 AND III-28

A mixture of 6.5 g of Resin (A-201) (Example III-27) or Resin (A-207)(Example III-28), 33.5 g of Resin (B-23), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (III-VII) shown below, 0.03 g of MethineDye (III-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at a rotation of 7×10³ r.p.m. for10 minutes to prepare a coating composition for a light-sensitive layer.The coating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 25g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR372##

COMPARATIVE EXAMPLE III-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example III-27, except for using Resin (R-III-5) shownbelow in place of 33.5 g of Resin (B-23) used in Example III-27.##STR373##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example III-2.The results obtained are shown in Table III-5 below.

                                      TABLE III-5                                 __________________________________________________________________________                         Example III-27                                                                        Example III-28                                                                        Comparative Example                      __________________________________________________________________________                                         III-5                                    Binder Resin         (A-201)/(B-23)                                                                        (A-207)/(B-23)                                                                        (A-201)/(R-III-5)                        Smoothness of Photoconductive                                                                      405     410     410                                      Layer (sec/cc)                                                                Mechanical Strength of                                                                             96      95      86                                       Photoconductive Layer (%)                                                     Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                           I (20° C., 65% RH)                                                                600     730     600                                                II (30° C., 80% RH)                                                               580     715     575                                                III (15° C., 30% RH)                                                              615     740     620                                      D.R.R. (%)                                                                              I (20° C., 65% RH)                                                                90      96      90                                                 II (30° C., 80% RH)                                                               87      94      85                                                 III (15° C., 30% RH)                                                              91      96      91                                       E.sub.1/10 (lux/sec)                                                                    I (20° C., 65% RH)                                                                10.3    8.5     11.8                                               II (30° C., 80% RH)                                                               9.8     8.0     11.0                                               III (15° C., 30% RH)                                                              12.5    10.1    13.3                                     Image Forming*.sup.8)                                                                   I (20° C., 65% RH)                                                                Good    Very good                                                                             Good                                     Performance                                                                             II (30° C., 80% RH)                                                               Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                          III (15° C., 30% RH)                                                              Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in image                                                           portion                                  Water Retentivity of Good    Good    Slight background stain                  Light-Sensitive Material                                                      Printing Durability  10,000  10,000  Background stain from                                         prints  prints  the start of printing                    __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleIII-2, except that same electro-static characteristics and image formingperformance were evaluated according to the following test methods.

*7J Measurement of Electrostatic Characteristics: E_(1/10)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 thereof was determined, and the exposure amountE_(1/10) (lux.sec) was calculated therefrom.

8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example III-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example III-28 using the resin (A') werevery good. The value of E_(1/10) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example III-5. Also, theoccurrence of unevenness in half tone area of continuous gradation andunevenness of small white spots in image portion was observed on theduplicated image when the ambient conditions at the time of the imageformation were high temperature and high humidity (II) and lowtemperature and low humidity (III). On the contrary, the light-sensitivematerials according to the present invention provided clear images freefrom background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example III-5,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention was satisfactory in allaspects of the surface smoothness and film strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, .it can be seen that the electrostaticcharacteristics are further improved by the use of the resin (A').

EXAMPLE III-29

A mixture of 5 g of Resin (A-223), 35 g of Resin (B-22), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bremophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example III-27 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example III-27, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor,10,000 prints of clear image were obtained.

EXAMPLES III-30 TO III-53

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example III-29, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table III-6 below inplace of 5 g of Resin (A-223) and 35 g of Resin (B-22) used in ExampleIII-29, respectively.

                  TABLE III-6                                                     ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        III-30        A-201         B-3                                               III-31        A-202         B-2                                               III-32        A-203         B-7                                               III-33        A-204         B-8                                               III-34        A-205         B-9                                               III-35        A-206         B-12                                              III-36        A-208         B-13                                              III-37        A-210         B-14                                              III-38        A-211         B-15                                              III-39        A-212         B-16                                              III-40        A-213         B-17                                              III-41        A-214         B-18                                              III-42        A-215         B-20                                              III-43        A-216         B-21                                              III-44        A-217         B-23                                              III-45        A-218         B-22                                              III-46        A-219         B-11                                              III-47        A-220         B-11                                              III-48        A-221         B-9                                               III-49        A-222         B-12                                              III-50        A-223         B-23                                              III-51        A-214         B-9                                               III-52        A-210         B-16                                              III-53        A-223         B-22                                              ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

EXAMPLE IV-1

A mixture of 8 g (solid basis) of Resin (A-7), 32 g (solid basis) ofResin (B-101), 200 g of photoconductive zinc oxide, 0.017 g of MethineDye (IV-I) shown below, 0.18 g of phthalic anhydride and 300 g oftoluene was dispersed by a homogenizer manufactured by Nippon Seiki K.K.) at a rotation of 6×10³ r.p.m. for 7 minutes to prepare a coatingcomposition for a light-sensitive layer. The coating composition wascoated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 20 g/m² followed by dryingat 100° C. for 30 seconds. The coated material was then allowed to standin a dark place at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR374##

COMPARATIVE EXAMPLE IV-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-1, except for using 32 g of Resin (R-IV-I) shownbelow in place of 32 g of Resin (B-101) used in Example IV-1. ##STR375##

COMPARATIVE EXAMPLE IV-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-1, except for using 32 g of Resin (R-IV-2) shownbelow in place of 32 g of Resin (B-101) used in Example IV-1. ##STR376##

COMPARATIVE EXAMPLE IV-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-1, except for using 32 g of Resin (R-IV-3) shownbelow in place of 32 g of Resin (B-101) used in Example IV-1. ##STR377##

With each of the light-sensitive material thus prepared, mechanicalstrength of photoconductive layer, electrostatic characteristics andimage forming performance were evaluated. The results obtained are shownin Table IV-1 below.

                                      TABLE IV-1                                  __________________________________________________________________________                              Comparative                                                                           Comparative                                                                           Comparative                                           Example IV-1                                                                          Example IV-1                                                                          Example IV-2                                                                          Example IV-3                        __________________________________________________________________________    Mechanical Strength of*.sup.1)                                                                   95%     75%     85%     86%                                photoconductive layer                                                         Electrostatic Characteristics*.sup.2)                                         V.sub.10 (-V)                                                                         I (20° C., 65% RH)                                                               635     600     610     600                                         II (30° C., 80% RH)                                                              620     575     590     585                                 D.R.R. (90 sec value) (%)                                                             I (20° C., 65% RH)                                                               88      84      85      85                                          II (30° C., 80% RH)                                                              83      78      80      81                                  E.sub.1/10                                                                            I (20° C., 65% RH)                                                               22      30      28      28                                  (erg/cm.sup.2)                                                                        II (30° C., 80% RH)                                                              26      35      34      33                                  E.sub.1/100                                                                           I (20° C., 65% RH)                                                               35      51      46      43                                  (erg/cm.sup.2)                                                                        II (30° C., 80% RH)                                                              43      77      70      68                                  Image Forming Performance*.sup.3)                                                     I (20° C., 65% RH)                                                               Very good                                                                             Scratches of                                                                          Scratches of                                                                          Scratches of                                                  fine lines and                                                                        fine lines and                                                                        fine lines and                                                letters,                                                                              letters,                                                              unevenness in                                                                         unevenness in                                                                         unevenness in                                                 half tone area                                                                        half tone area                                                                        half tone area                              II (30° C., 80% RH)                                                              Very good                                                                             Scratches of                                                                          Scratches of                                                                          Scratches of                                                  fine lines and                                                                        fine lines and                                                                        fine lines and                                                letters,                                                                              letters,                                                                              letters,                                                      unevenness in                                                                         unevenness in                                                                         unevenness in                                                 half tone area                                                                        half tone area                                                                        half tone area                      __________________________________________________________________________

The evaluation of each item shown in Table IV-1 was conducted in thefollowing manner.

1) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1500 times)rubbed with emery paper (#000) under a load of 50 g/cm² using a Heidon14 Model surface testing machine manufactured by Shinto Kagaku K. K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*2) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*3) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent IsoparG manufactured by Esso Chemical K. K.) and fixed. The duplicated imageobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II).

As can be seen from the results shown in Table IV-1, the light-sensitivematerial according to the present invention had good electrostaticcharacteristics. The duplicated image obtained thereon was clear andfree from background fog. On the contrary, with the light-sensitivematerials of Comparative Examples IV-1, IV-2 and IV-3, the decrease inphotosensitivity (E_(1/10) and E_(1/100)) occurred, and in theduplicated images the scratches of fine lines and letters were observedand a background fog remained unremoved after the rinse treatment.Further, the occurrence of unevenness in half tone areas of continuousgradation of the original was observed regardless of the electrostaticcharacteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller the value, the less the background fog in the non-imageareas. More specifically, it is required that the remaining potential isdecreased to -10V or less. Therefore, an amount of exposure necessary tomake the remaining potential below -10V is an important factor. In thescanning exposure system using a semiconductor laser beam, it is quiteimportant to make the remaining potential below -10V by a small exposureamount in view of a design for an optical system of a duplicator (suchas cost of the device, and accuracy of the optical system).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlyusing the binder resin according to the present invention.

EXAMPLE IV-2

A mixture of 6 g (solid basis) of Resin (A-10), 34 g (solid basis) ofResin (B-102), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (IV-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example IV-1 toprepare an electrophotographic light-sensitive material. ##STR378##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table IV-2below.

                  TABLE IV-2                                                      ______________________________________                                                              Example IV-2                                            ______________________________________                                        Smoothness of Photoconductive Layer*.sup.4)                                                           300                                                   Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                              I (20° C., 65% RH)                                                                    640                                                            II (30° C., 80% RH)                                                                   625                                               D.R.R.       I (20° C., 65% RH)                                                                    88                                                (90 sec value) (%)                                                                         II (30° C., 80% RH)                                                                   83                                                E.sub.1/10 (erg/cm.sup.2)                                                                  I (20° C., 65% RH)                                                                    20                                                             II (30° C., 80% RH)                                                                   25                                                E.sub.1/100 (erg/cm.sup.2)                                                                 I (20° C., 65% RH)                                                                    31                                                             II (30° C., 80% RH)                                                                   40                                                Image Forming Performance                                                                I (20° C., 65% RH)                                                                  Very good                                                        II (30° C., 80% RH)                                                                 Very good                                             Contact Angle with Water*.sup.5) (°)                                                            0                                                    Printing Durability.sup.*6)                                                                           10,000 prints                                         ______________________________________                                    

The evaluation of each item shown in Table IV-2 was conducted in thefollowing manner.

*4) smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*5) Contact Anqle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ELP-EX (produced by Fuji Photo Film Co., .Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *3) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *5) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52", manufactured by Sakurai Seisakusho K. K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table IV-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic, as shown by a small contact angle of0° with water. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES IV-3 TO IV-20

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example IV-2, except for using each ofResins (A) and Resins (B) shown in Table IV-3 below in place of Resin(A-10) and Resin (B-102) used in Example IV-2, respectively.

                  TABLE IV-3                                                      ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        IV-3          A-2           B-104                                             IV-4          A-3           B-105                                             IV-5          A-4           B-106                                             IV-6          A-5           B-107                                             IV-7          A-6           B-108                                             IV-8          A-8           B-109                                             IV-9          A-9           B-110                                             IV-10         A-11          B-112                                             IV-11         A-12          B-113                                             IV-12         A-13          B-114                                             IV-13         A-14          B-115                                             IV-14         A-16          B-116                                             IV-15         A-17          B-118                                             IV-16         A-19          B-119                                             IV-17         A-22          B-120                                             IV-18         A-23          B-122                                             IV-19         A-27          B-124                                             IV-20         A-28          B-127                                             ______________________________________                                    

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in ExampleIV-2, and good results were obtained.

As a result of the evaluation on image forming performance of eachlight-sensitive material, it was found that clear duplicated imageshaving good reproducibility of fine lines and letters and no occurrenceof unevenness in half tone areas without the formation of background fogwere obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example IV-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics, andprinting property.

EXAMPLES IV-21 TO IV-24

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example IV-1, except for using each of thedye shown in Table IV-4 below in place of Methine Dye (IV-I) used inExample IV-1.

                                      TABLE IV-4                                  __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    IV-21                                                                              (IV-III)                                                                             ##STR379##                                                        IV-22                                                                              (IV-IV)                                                                              ##STR380##                                                        IV-23                                                                              (IV-V)                                                                               ##STR381##                                                        IV-24                                                                              (IV-VI)                                                                              ##STR382##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES IV-25 AND IV-26

A mixture of 6.5 g of Resin (A-1) (Example IV-25) or Resin (A-18)(Example IV-26), 33.5 g of Resin (B-130), 200 g of zinc oxide, 0.02 g ofuranine, 0.035 g of Rose Bengal, 0.025 g of bremophenol blue, 0.18 g ofp-hydroxybenzoic acid and 300 g of toluene was dispersed by ahomogenizer at a rotation of 7×10³ r.p.m. for 6 minutes to prepare acoating composition for a light-sensitive layer. The coating compositionwas coated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 25 g/m², and dried for 20seconds at 110° C. Then, the coated material was allowed to stand in adark place for 24 hours under the -conditions of 20° C. and 65% RH toprepare each electrophotographic light-sensitive material.

COMPARATIVE EXAMPLE IV-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example IV-25, except for using 33.5 g of Comparative Resin(R-IV-2) described above in place of 33.5 g of Resin (B-130) used inExample IV-25.

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example IV-2.The results obtained are shown in Table IV-5 below.

                                      TABLE IV-5                                  __________________________________________________________________________                       Example IV-25                                                                         Example IV-26                                                                         Comparative Example IV-4                   __________________________________________________________________________    Binder Resin       (A-1)/(B-130)                                                                         (A-18)/(B-130)                                                                        (A-1)/(R-IV-2)                             Smoothness of Photoconductive                                                                    280     290     260                                        Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                               570     650     550                                                 II (30° C., 80% RH)                                                              550     635     525                                        D.R.R. (%)                                                                             I (20° C., 65% RH)                                                               85      9 2     83                                                  II (30° C., 80% RH)                                                              80      87      77                                         E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                               10.5    7.6     13.5                                                II (30° C., 80% RH)                                                              11.3    8.8     14.2                                       E.sub.1/100 (lux/sec)                                                                  I (20° C., 65% RH)                                                               17      12      21                                                  II (30° C., 80% RH)                                                              19      14      23                                         Image Forming*.sup.8)                                                                  I (20° C., 65% RH)                                                               Good    Very good                                                                             Edge mark of cutting                       Performance                                                                            II (30° C., 80% RH)                                                              Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                  Contact Angle with Water (°)                                                              0       0       0                                          Printing Durability                                                                              10,000   10,000 Background stain due to                                       prints  prints  edge mark of cutting                                                          occurred from the start                                                       of printing                                __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleIV-2, except that same electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/10) and E1/100

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux.sec) was calculatedtherefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making/machine ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited a most same properties with respect to the surfacesmoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example IV-4 had the particularly large value ofphotosensitivity E_(1/100), and this tendency increased under the hightemperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive materials accordingto the present invention were good. Particularly, those of Example IV-26using the resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example IV-4. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example IV-4,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that only thelight-sensitive materials according to the present invention can provideexcellent performance.

EXAMPLES IV-27 TO IV-42

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example IV-25, except for using 6.5 g ofeach of Resin (A) and 33.5 g of each of Resin (B) shown in Table IV-6below in place of 6.5 g of Resin (A-1) and 33.5 g of Resin (B-130) usedin Example IV-25, respectively.

                  TABLE IV-6                                                      ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        IV-27         A-2           B-111                                             IV-28         A-4           B-117                                             IV-29         A-5           B-121                                             IV-30         A-8           B-123                                             IV-31         A-9           B-124                                             IV-32         A-20          B-126                                             IV-33         A-21          B-128                                             IV-34         A-22          B-129                                             IV-35         A-24          B-130                                             IV-36         A-25          B-103                                             IV-37         A-26          B-122                                             IV-38         A-29          B-124                                             IV-39         A-17          B-115                                             IV-40         A-19          B-116                                             IV-41         A-14          B-118                                             IV-42         A-15          B-119                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog even under severe condition of high temperature and highhumidity (30° C. and 80% RH). Further, when these materials wereemployed as offset master plate precursors, more than 10,000 prints of aclear image free from background stains were obtained respectively.Moreover, the light-sensitive materials using the resin (A') containinga methacrylate component substituted with the specific aryl groupexhibited better performance.

EXAMPLE V-1

A mixture of 8 g (solid basis) of Resin (A-104), 32 g (solid basis) ofResin (B-101), 200 g of photoconductive zinc oxide, 0.017 g of MethineDye (V-I) shown below, 0.18 g of phthalic anhydride and 300 g of toluenewas dispersed by a homogenizer manufactured by Nippon Seiki K. K.) at arotation of 6×10³ r.p.m. for 7 minutes to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar at a dry coverage of 25 g/m² followed by drying at 100° C.for 30 seconds The coated material was then allowed to stand in a darkplace at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR383##

COMPARATIVE EXAMPLE V-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-1, except for using 32 g of Resin (R-V-1) shownbelow in place of 32 g of Resin (B-101) used in Example V-1. ##STR384##

COMPARATIVE EXAMPLE V-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-1, except for using 32 g of Resin (R-V-2) shownbelow in place of 32 g of Resin (B-101) used in Example V-1. ##STR385##

COMPARATIVE EXAMPLE V-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-1, except for using 32 g of Resin (R-V-3) shownbelow in place of 32 g of Resin (B-101) used in Example V-1. ##STR386##

With each of the light-sensitive materials thus prepared, mechanicalstrength of photoconductive layer, electrostatic characteristics andimage forming perform-ance were evaluated. The results obtained areshown in Table V-1 below.

                                      TABLE V-1                                   __________________________________________________________________________                           Comparative                                                                           Comparative                                                                           Comparative                                            Example V-1                                                                          Example V-1                                                                           Example V-2                                                                           Example V-3                            __________________________________________________________________________    Mechanical Strength of                                                                        96%    74%     83%     85%                                    photoconductive layer*.sup.1)                                                 Electrostatic Characteristics*.sup.2)                                         V.sub.10 (-V)                                                                       I (20° C., 65% RH)                                                               780    800     770     785                                          II (30° C., 80% RH)                                                              760    770     750     770                                    D.R.R. (90 sec value) (%)                                                           I (20° C., 65% RH)                                                               90     85      89      91                                           II (30° C., 80% RH)                                                              87     83      86      87                                     E.sub.1/10                                                                          I (20° C., 65% RH)                                                               8.5    11.4    10.1    9.5                                    (erg/cm.sup.2)                                                                      II (30° C., 80% RH)                                                              8.8    10.9    9.7     9.0                                    E.sub.1/100                                                                         I (20° C., 65% RH)                                                               14     20      17      15                                     (erg/cm.sup.2)                                                                      II (30° C., 80% RH)                                                              15     21      18      17                                     Image Forming Performance*.sup.3)                                                   I (20° C., 65% RH)                                                               Very good                                                                            Slight  Good    Good                                                          unevenness in                                                                 half tone area                                               II (30° C., 80% RH)                                                              Very good                                                                            Unevenness in                                                                         Unevenness in                                                                         Unevenness in                                          half tone                                                                            half tone area                                                                        half tone area                                                 area, white                                                                   spots in image                                                                portion, slight                                                               scratches of                                                                  fine lines and                                                                letters                                                       __________________________________________________________________________

The evaluation of each item shown in Table V-1 was conducted in thefollowing manner.

1) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1500 times)rubbed with emery paper (#1000) under a load of 50 g/cm² using a Heidon14 Model surface testing/machine manufactured by Shinto Kagaku K. K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*2) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*3) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent IsoparG manufactured by Esso Chemical K. K.) and fixed. The duplicated imageobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II).

As can be seen from the results shown in Table V-1, the light-sensitivematerial according to the present invention had good electrostaticcharacteristics. The duplicated image obtained thereon was clear andfree from background fog. On the contrary, with the light-sensitivematerials of Comparative Examples V-1, V-2 and V-3 the decrease inphotosensitivity (E_(1/10) and E_(1/100)) occurred, and in theduplicated images the scratches of fine lines and letters were observedand a background fog remained unremoved after the rinse treatment.Further, the occurrence of unevenness in half tone areas of continuousgradation of the original was observed regardless of the electrostaticcharacteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller the value, the less the background fog in the non-imageareas. More specifically, it is required that the remaining potential isdecreased to -10V or less. Therefore, an amount of exposure necessary tomake the remaining potential below -10 V is an important factor. In thescanning exposure system using a semiconductor laser beam, it is quiteimportant to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlyusing the binder resin according to the present invention.

EXAMPLE V-2

A mixture of 6 g (solid basis) of Resin (A-128), 34 g (solid basis) ofResin (B-102), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (V-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example V-1 toprepare an electrophotographic light-sensitive material. ##STR387##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table V-2below.

                  TABLE V                                                         ______________________________________                                                                Example V-2                                           ______________________________________                                        Smoothness of Photoconductive Layer*.sup.4)                                                             310                                                 Electrostatic Characteristics                                                 V.sub.10 (-V)   I (20° C., 65% RH)                                                                   805                                                             II (30° C., 80% RH)                                                                  785                                             D.R.R.          I (20° C., 65% RH)                                                                   91                                              (90 sec value) (%)                                                                            II (30° C., 80% RH)                                                                  88                                              E.sub.1/10 (erg/cm.sup.2)                                                                     I (20° C., 65% RH)                                                                   9.0                                                             II (30° C., 80% RH)                                                                  10.5                                            E.sub.1/100 (erg/cm.sup.2)                                                                    I (20° C., 65% RH)                                                                   15                                                              II (30° C., 80% RH)                                                                  18                                              Image Forming Performance                                                                     I (20° C., 65% RH)                                                                   Very good                                                       II (30° C., 80% RH)                                                                  Very good                                       Contact Angle with Water*.sup.5)                                                              (°)    0                                               Printing Durability*.sup.6)   10,000 prints                                   ______________________________________                                    

The evaluation of each item shown in Table V-2 was conducted in thefollowing manner.

*4) smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*5) Contact Anqle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ELP-EX (produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *3) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *5) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52",manufactured by Sakurai Seisakusho K. K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table V-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic, as shown by a small contact angle of0° with water. On practical printing using the resulting master plate,10,000 prints of clear image without background stains were obtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES V-3 TO V-20

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example V-2, except for using each of Resins(A) and Resins (B) shown in Table V-3 below in place of Resin (A-128)and Resin (B-102) used in Example V-2, respectively.

                  TABLE V-3                                                       ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        V-3           A-103         B-103                                             V-4           A-105         B-104                                             V-5           A-106         B-105                                             V-6           A-108         B-106                                             V-7           A-109         B-107                                             V-8           A-110         B-108                                             V-9           A-111         B-110                                             V-10          A-116         B-111                                             V-11          A-119         B-113                                             V-12          A-120         B-115                                             V-13          A-121         B-116                                             V-14          A-122         B-118                                             V-15          A-124         B-119                                             V-16          A-125         B-120                                             V-17          A-127         B-122                                             V-18          A-129         3-126                                             V-19          A-130         B-127                                             V-20          A-133         B-130                                             ______________________________________                                    

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in Example V-2,and good results were obtained.

As a result of the evaluation on image forming performance of eachlight-sensitive material, it was found that clear duplicated imageshaving good reproducibility of fine lines and letters and no occurrenceof unevenness in half tone areas without the formation of background fogwere obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example V-2, more than 10,000 good prints wereobtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES V-21 TO V-24

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example V-1, except for using each of thedye shown in Table V-4 below in place of Methine Dye (V-I) used inExample V-1.

                                      TABLE V-4                                   __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    V-21 (V-III)                                                                              ##STR388##                                                        V-22 (V-IV)                                                                               ##STR389##                                                        V-23 (V-V)                                                                                ##STR390##                                                        V-24 (V-VI)                                                                               ##STR391##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES V-25 AND V-26

A mixture of 6.5 g of Resin (A-102) (Example V-25) or Resin(A-132)(Example V-26), 33.5 g of Resin (B-123), 200 g of zinc oxide,0.02 g of uranine, 0.035 g of Rose Bengal, 0.025 g of bremophenol blue,0.18 g of p-hydroxybenzoic acid and 300 g of toluene was dispersed by ahomogenizer at a rotation of 7×10³ r.p.m. for 6 minutes to prepare acoating composition for a light-sensitive layer. The coating compositionwas coated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 25 g/m² and dried for 20seconds at 110° C. Then, the coated material was allowed to stand in adark place for 24 hours under the conditions of 20° C. and 65% RH toprepare each electrophotographic light-sensitive material.

COMPARATIVE EXAMPLE V-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example V-25, except for using 33.5 g of Comparative Resin(R-V-2) described above in place of 33.5 g of Resin (B-123) used inExample V-25.

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example V-2. Theresults obtained are shown in Table V-5 below.

                                      TABLE V-5                                   __________________________________________________________________________                       Example V-25                                                                          Example V-26                                                                          Comparative Example V-4                    __________________________________________________________________________    Binder Resin       (A-102)/(B-123)                                                                       (A-132)/(B-123)                                                                       (A-102)/(R-V-2)                            Smoothness of Photoconductive                                                                    330     340     320                                        Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                               585     820     565                                                 II (30° C., 80% RH)                                                              565     795     540                                        D.R.R. (%)                                                                             I (20° C., 65% RH)                                                               89      93      85                                                  II (30° C., 80% RH)                                                              84      90      79                                         E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                               12.5    8.8     14.3                                                II (30° C., 80% RH)                                                              12.8    9.1     15.0                                       E.sub.1/100 (lux/sec)                                                                  I (20° C., 65% RH)                                                               22      14      26                                                  II (30° C., 80% RH)                                                              23      15      28                                         Image Forming*.sup.8)                                                                  I (20° C., 65% RH)                                                               Good    Very good                                                                             Unevenness in half tone                                                       area, slight scratches                                                        of fine lines                              Performance                                                                            II (30° C., 80% RH)                                                              Good    Very good                                                                             Severe unevenness                                                             in half tone area,                                                            scratches of fine                                                             lines and letters                          Contact Angle with Water (°)                                                              0       0       0                                          Printing Durability                                                                              10,000  10,000  Unevenness in                                                 prints  prints  image portion                                                                 occurred from the                                                             start of printing                          __________________________________________________________________________

The characteristics were evaluated in the same manner as in Example V-2,except that same electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Measurement of Electrostatic Characteristics: E_(1/10) and E_(1/100)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux.sec) was calculatedtherefrom.

*8) image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine (ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost same properties with respect to the surfacesmoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example V-4 had the particularly large value ofphotosensitivity E_(1/100), and this tendency increased under the hightemperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive materials accordingto the present invention were good. Particularly, those of Example V-26using the resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example V-4. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example V-4,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that only thelight-sensitive materials according to the present invention can provideexcellent performance.

EXAMPLES V-27 TO V-42

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example V-25, except for using 6.5 g of eachof Resin (A) and 33.5 g of each of Resin (B) shown in Table V-6 below inplace of 6.5 g of Resin (A-102) and 33.5 g of Resin (B-123) used inExample V-25, respectively.

                  TABLE V-6                                                       ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        V-27          A-101         B-104                                             V-28          A-103         B-105                                             V-29          A-105         B-106                                             V-30          A-106         B-107                                             V-31          A-107         B-109                                             V-32          A-110         B-110                                             V-33          A-113         B-111                                             V-34          A-114         B-113                                             V-35          A-115         B-115                                             V-36          A-117         B-117                                             V-37          A-119         B-120                                             V-38          A-120         B-121                                             V-39          A-121         B-124                                             V-40          A-129         B-125                                             V-41          A-132         B-128                                             V-42          A-125         B-129                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog even under severe condition of high temperature and highhumidity (30° C. and 80% RH). Further, when these materials wereemployed as offset master plate precursors, more than 10,000 prints of aclear image free from background stains were obtained respectively.Moreover, the light-sensitive materials using the resin (A') containinga methacrylate component substituted with the specific aryl groupexhibited better performance.

EXAMPLE VI-1

A mixture of 6 g (solid basis) of Resin (A-1), 34 g (solid basis) ofResin (B-201), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (VI-I) shown below, 0.15 g of phthalic anhydride and 300 g oftoluene was dispersed by a homogenizer manufactured by Nippon Seiki K.K.) at 6×10³ r.p.m. for 10 minutes to prepare a coating composition fora light-sensitive layer. The coating composition was coated on paper,which had been subjected to electrically conductive treatment, by a wirebar at a dry coverage of 20 g/m², followed by drying at 110° C. for 10seconds. The coated material was then allowed to stand in a dark placeat 20° C. and 65% RH (relative humidity) for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR392##

COMPARATIVE EXAMPLE VI-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-1, except for using 34 g of Resin (R-VI-1) shownbelow in place of 34 g of Resin (B-201) used in Example VI-1. ##STR393##

COMPARATIVE EXAMPLE VI-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-1, except for using 34 g of Resin (R-VI-2) shownbelow in place of 34 g of Resin (B-201) used in Example VI-1. ##STR394##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table VI-1 below.

                                      TABLE VI-1                                  __________________________________________________________________________                               Comparative                                                                           Comparative                                                   Example VI-1                                                                          Example VI-1                                                                          Example VI-2                               __________________________________________________________________________    Electrostatic Characteristics*.sup.1)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                               590     575     585                                                 II (30° C., 80% RH)                                                              580     560     575                                        D.R.R. (%)                                                                             I (20° C., 65% RH)                                                               85      83      85                                                  II (30° C., 80% RH)                                                              80      78      80                                         E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                               28      39      34                                                  II (30° C., 80% RH)                                                              30      44      38                                         E.sub.1/100 (lux/sec)                                                                  I (20° C., 65% RH)                                                               43      64      55                                                  II (30° C., 80% RH)                                                              48      73      61                                         Image Forming                                                                          I (20° C., 65% RH)                                                               Very    Scratches of                                                                          Scratches of                               Performance*.sup.2)                                                                              good    fine lines and                                                                        fine lines and                                                        letters letters                                                               unevenness in                                                                         unevenness in                                                         half tone area                                                                        half tone area                                      II (30° C., 80% RH)                                                              Very    Scratches of                                                                          Scratches of                                                  good    fine lines and                                                                        fine lines and                                                        letters letters                                                               unevenness in                                                                         unevenness in                                                         half tone area                                                                        half tone area                             __________________________________________________________________________

The evaluation of each item shown in Table VI-1 was conducted in thefollowing manner.

1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth were measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent IsoparG manufactured by Esso Chemical K. K.) and fixed. The duplicated imageobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II).

As can be seen from the results shown in Table VI-1, the light-sensitivematerial according to the present invention had good electrostaticcharacteristics. The duplicated image obtained thereon was clear andfree from background fog. On the contrary, with the light-sensitivematerials of Comparative Examples VI-1 and VI-2 the decrease inphotosensitivity (E_(1/10) and E_(1/100)) occurred, and in theduplicated images the scratches of fine lines and letters were observedand a slight background fog remained without removing after the rinsetreatment. Further, the occurrence of unevenness in half tone areas ofcontinuous gradation of the original was observed regardless of theelectrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller the value, the less the background fog in the non-imageareas. More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlyusing the binder resin according to the present invention.

EXAMPLE VI-2

A mixture of 5 g (solid basis) of Resin (A-7), 35 g (solid basis) ofResin (B-202), 200 g of photoconductive zinc oxide, 0.020 g of MethineDye (VI-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example VI-1 toprepare an electrophotographic light-sensitive material. ##STR395##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table VI-2below.

                  TABLE VI-2                                                      ______________________________________                                                                Example                                                                       VI-2                                                  ______________________________________                                        Smoothness of Photoconductive Layer*.sup.3)                                                             480                                                 (sec/cc)                                                                      Electrostatic Characteristics                                                 V.sub.10 (-V)   I (20° C., 65% RH)                                                                   660                                                             II (30° C., 80% RH)                                                                  650                                             D.R.R.          I (20° C., 65% RH)                                                                   87                                              (90 sec value) (%)                                                                            II (30° C., 80% RH)                                                                  85                                              E.sub.1/10 (erg/cm.sup.2)                                                                     I (20° C., 65% RH)                                                                   19                                                              II (30° C., 80% RH)                                                                  20                                              E.sub.1/100 (erg/cm.sup.2)                                                                    I (20° C., 65% RH)                                                                   29                                                              II (30° C., 80% RH)                                                                  31                                              Image Forming Performance                                                                     I (20° C., 65% RH)                                                                   Very good                                                       II (30° C., 80% RH)                                                                  Very good                                       Contact Angle with Water*.sup.4)                                                              (°)    10 or less                                      Printing Durability*.sup.5)   10,000 prints                                   ______________________________________                                    

The evaluation of each item shown in Table VI-2 was conducted in thefollowing manner.

*3) smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*4) Contact Anqle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ELP-EX (produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*5) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *4) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52",manufactured by Sakurai Seisakusho K. K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table VI-2, the light-sensitivematerial according to the present invention had good surface smoothness,film strength and electrostatic characteristics of the photoconductivelayer. The duplicated image obtained was clear and free from backgroundfog in the non-image area. These results appear to be due to sufficientadsorption of the binder resin onto the photoconductive substance andsufficient covering of the surface of the particles with the binderresin. For the same reason, when it was used as an offset master plateprecursor, oil-desensitization of the offset master plate precursor withan oil-desensitizing solution was sufficient to render the non-imageareas satisfactorily hydrophilic, as shown by a small contact angle of10° or less with water. On practical printing using the resulting/masterplate, 10,000 prints of clear image without background stains wereobtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES VI-3 TO VI-18

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VI-2, except for using each ofResins (A) and Resins (B) shown in Table VI-3 below in place of Resin(A-7) and Resin (B-202) used in Example VI-2, respectively.

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in ExampleVI-2. The results obtained are shown in Table VI-3 below.

                                      TABLE VI-3                                  __________________________________________________________________________          Resin                                                                             Resin      D.R.R.                                                                             E.sub.1/10                                                                          E.sub.1/100                                   Example                                                                             (A) (B)  V.sub.10 (-V)                                                                       (%)  (erg/cm.sup.2)                                                                      (erg/cm.sup.2)                                __________________________________________________________________________    VI-3  A-2 B-202                                                                              590   80   30    47                                            VI-4  A-3 B-203                                                                              670   83   21    32                                            VI-5  A-4 B-204                                                                              585   80   31    49                                            VI-6  A-5 B-205                                                                              590   81   30    46                                            VI-7  A-6 B-207                                                                              660   83   20    30                                            VI-8  A-8 B-208                                                                              660   82   19    30                                            VI-9  A-9 B-212                                                                              580   79   32    39                                            VI-10 A-12                                                                              B-210                                                                              580   80   30    44                                            VI-11 A-13                                                                              B-207                                                                              585   79   34    50                                            VI-12 A-15                                                                              B-211                                                                              570   78   33    48                                            VI-13 A-17                                                                              B-214                                                                              600   81   22    34                                            VI-14 A-22                                                                              B-216                                                                              590   80   29    44                                            VI-15 A-23                                                                              B-222                                                                              650   82   22    34                                            VI-16 A-26                                                                              B-223                                                                              560   78   36    49                                            VI-17 A-27                                                                              B-224                                                                              600   80   28    42                                            VI-18 A-29                                                                              B-226                                                                              665   83   20    33                                            __________________________________________________________________________

The electrostatic characteristics were evaluated under the condition of30° C. and 80% RH.

As a result of the evaluation on image forming performance of eachlight-sensitive material, it was found that clear duplicated imageshaving good reproducibility of fine lines and letters and no occurrenceof unevenness in half tone areas without the formation of background fogwere obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example VI-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty. Also, it can be seen that the electrostatic characteristicsare further improved by the use of the resin (A').

EXAMPLES VI-19 TO VI-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VI-1, except for using each of thedye shown in Table VI-4 below in place of Cyanine Dye (VI-I) used inExample VI-1.

                                      TABLE VI-4                                  __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    VI-19                                                                              (VI-III)                                                                             ##STR396##                                                        VI-20                                                                              (VI-IV)                                                                              ##STR397##                                                        VI-21                                                                              (VI-V)                                                                               ##STR398##                                                        VI-22                                                                              (VI-VI)                                                                              ##STR399##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES VI-23 AND VI-24

A mixture of 6.5 g of Resin (A-1) (Example VI-23) or Resin (A-29)(Example VI-24), 33.5 g of Resin (B-217), 200 g of zinc oxide, 0.02 g ofuranine, 0.03 g of Methine Dye (VI-VII) shown below, 0.03 g of MethineDye (VI-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and 300 g oftoluene was dispersed by a homogenizer at a rotation of 7×10³ r.p.m. for10 minutes to prepare a coating composition for a light-sensitive layer.The coating composition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar at a dry coverage of 20g/m², and dried for 20 seconds at 110° C. Then, the coated material wasallowed to stand in a dark place for 24 hours under the conditions of20° C. and 65% RH to prepare each electrophotographic light-sensitivematerial. ##STR400##

COMPARATIVE EXAMPLE VI-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VI-23, except for using 33.5 g of Resin (R-VI-3)shown below in place of 33.5 g of Resin (B-217) used in Example VI-23.##STR401##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example VI-2.The results obtained are shown in Table VI-5 below.

                                      TABLE VI-5                                  __________________________________________________________________________                       Example VI-23                                                                         Example VI-24                                                                         Comparative Example VI-3                   __________________________________________________________________________    Binder Resin       (A-1)/(B-217)                                                                         (A-29)/(B-217)                                                                        (A-1)/(R-VI-3)                             Smoothness of Photoconductive                                                                    550     600     580                                        Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.6)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                               590     665     590                                                 II (30° C., 80% RH)                                                              580     650     575                                        D.R.R. (%)                                                                             I (20° C., 65% RH)                                                               95      98      94                                                  II (30° C., 80% RH)                                                              92      95      91                                         E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                               11.2    8.5     12.8                                                II (30° C., 80% RH)                                                              11.6    8.8     13.3                                       E.sub.1/100 (lux/sec)                                                                  I (20° C., 65% RH)                                                               16      12      21                                                  II (30° C., 80% RH)                                                              17      13      23                                         Image Forming*.sup.7)                                                                  I (20° C., 65% RH)                                                               Good    Very good                                                                             Edge mark of cutting                       Performance                                                                            II (30° C., 80% RH)                                                              Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                  Contact Angle with Water (°)                                                              10 or less                                                                            10 or less                                                                            10 or less                                 Printing Durability                                                                              10,000  10,000  Background stain due to                                       prints  prints  edge mark of cutting                                                          occurred from the start                                                       of printing                                __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleVI-2, except that same electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*6) Measurement of Electrostatic Characteristics: E_(1/10) and E_(1/100)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux.sec) was calculatedtherefrom.

*7) image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine ELP-404V manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost the same properties with respect to thesurface smoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example VI-3 had the particularly large value ofphotosensitivity E_(1/100), and this tendency increased under the hightemperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive material accordingto the present invention were good. Further, those of Example VI-24using the resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image area's in thelight-sensitive material of Comparative Example VI-3. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example VI-3,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that only thelight-sensitive materials according to the present invention can provideexcellent performance.

EXAMPLE VI-25

A mixture of 5 g of Resin (A-22), 35 g of Resin (B-222), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bremophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example VI-24 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example VI-24, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH). Further, when the material was employed as an offset master plateprecursor, 10,000 prints of clear image were obtained.

EXAMPLES VI-26 TO VI-37

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VI-25, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table VI-6 below inplace of 5 g of Resin (A-22) and 35 g of Resin (B-222 used in ExampleVI-25, respectively.

                  TABLE VI-6                                                      ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        VI-26         A-1           B-206                                             VI-27         A-2           B-209                                             VI-28         A-4           B-210                                             VI-29         A-5           B-212                                             VI-30         A-9           B-213                                             VI-31         A-15          B-215                                             VI-32         A-20          B-217                                             VI-33         A-21          B-218                                             VI-34         A-22          B-219                                             VI-35         A-25          B-221                                             VI-36         A-26          B-225                                             VI-37         A-29          B-209                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionof high temperature and high humidity (30° C. and 80% RH). Further, whenthese materials were employed as offset master plate precursors, morethan 10,000 prints of a clear image free from background stains wereobtained respectively.

EXAMPLE VII-1

A mixture of 5 g (solid basis) of Resin (A-106), 35 g (solid basis) ofResin (B-201), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (VII-I) shown below, 0.45 g of phthalic anhydride and 300 g oftoluene was dispersed by a homogenizer manufactured by Nippon Seiki K.K.) at a rotation of 7×10³ r.p.m. for 10 minutes to prepare a coatingcomposition for a light-sensitive layer. The coating composition wascoated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 20 g/m², followed bydrying at 110° C. for 10 seconds. The coated material was then allowedto stand in a dark place at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR402##

COMPARATIVE EXAMPLE VII-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-1, except for using 35 g of Resin (R-VII-l)shown below in place of 35 g of Resin (B-201) used in Example VII-1.##STR403##

COMPARATIVE EXAMPLE VII-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-1, except for using 35 g of Resin (R-VII-2)shown below in place of 35 g of Resin (B-201) used in Example VII-1.##STR404##

With each of the light-sensitive materials thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table VII-1 below.

                  TABLE VII-1                                                     ______________________________________                                                           Comparative                                                                              Comparative                                                 Example                                                                              Example    Example                                                     VII-1  VII-1      VII-2                                           ______________________________________                                        Electrostatic                                                                 Characteristics*.sup.1)                                                       V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                   600      590        595                                         II (30° C., 80% RH)                                                                  590      580        580                                         D.R.R. (90 sec value)                                                         (%)                                                                           I (20° C., 65% RH)                                                                   83       80         81                                          II (30° C., 80% RH)                                                                  79       75         77                                          E.sub.1/10 (erg/cm.sup.2)                                                     I (20° C., 65% RH)                                                                   25       30         27                                          II (30° C., 80% RH)                                                                  30       35         33                                          E.sub.1/100 (erg/cm.sup.2)                                                    I (20° C., 65% RH)                                                                   40       50         45                                          II (30° C., 80% RH)                                                                  49       59         54                                          Image Forming                                                                 Performance*.sup.2)                                                           I (20° C., 65% RH)                                                                   Very     Scratches of                                                                             Scratches of                                              good     fine lines and                                                                           fine lines and                                                     letters,   letters,                                                           unevenness in                                                                            unevenness in                                                      half tone area                                                                           half tone area                              II (30° C., 80% RH)                                                                  Very     Scratches of                                                                             Scratches of                                              good     fine lines and                                                                           fine lines and                                                     letters,   letters,                                                           unevenness in                                                                            unevenness in                                                      half tone area                                                                           half tone area                              ______________________________________                                    

The evaluation of each item shown in Table VII-1 was conducted in thefollowing manner.

1) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP-428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. Further, in the same manner as described above thetime required for decay of the surface potential V₁₀ to one-hundredthwas measured, and the exposure amount E_(1/100) (erg/cm²) was calculatedtherefrom. The measurements were conducted under ambient condition of20° C. and 65% RH (I) or 30° C. and 80% RH (II).

*2) Image Forming Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent IsoparG manufactured by Esso Chemical K. K.) and fixed. The duplicated imageobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II).

As can be seen from the results shown in Table VII-1, thelight-sensitive material according to the present invention had goodelectrostatic characteristics. The duplicated image obtained thereon wasclear and free from background fog. On the contrary, with thelight-sensitive materials of Comparative Examples VII-1 and VII-2 thedecrease in photosensitivity (E_(1/10) and E_(1/100)) occurred, and inthe duplicated images the scratches of fine lines and letters wereobserved and a slight background fog remained without removing after therinse treatment. Further, the occurrence of unevenness in half toneareas of continuous gradation of the original was observed regardless ofthe electrostatic characteristics.

The value of E_(1/100) is largely different between the light-sensitivematerial of the present invention and those of the comparative examples.The value of E_(1/100) indicates an electrical potential remaining inthe non-image areas after exposure at the practice of image formation.The smaller the value, the less the background fog in the non-imageareas. More specifically, it is required that the remaining potential isdecreased to -10 V or less. Therefore, an amount of exposure necessaryto make the remaining potential below -10 V is an important factor. Inthe scanning exposure system using a semiconductor laser beam, it isquite important to make the remaining potential below -10 V by a smallexposure amount in view of a design for an optical system of aduplicator (such as cost of the device, and accuracy of the opticalsystem).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance and being advantageously employed particularly in a scanningexposure system using a semiconductor laser beam can be obtained onlyusing the binder resin according to the present invention.

EXAMPLE VII-2

A mixture of 5 g (solid basis) of Resin (A-104), 35 g (solid basis) ofResin (B-202), 200 g of photoconductive zinc oxide, 0,020 g of MethineDye (VII-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example VII-1 toprepare an electrophotographic lightsensitive material. ##STR405##

With the light-sensitive material thus-prepared, a film property interms of surface smoothness, electrostatic characteristics and imageforming performance were evaluated. Further, printing property wasevaluated when it was used as an electrophotographic lithographicprinting plate precursor. The results obtained are shown in Table VII-2below.

                  TABLE VII-2                                                     ______________________________________                                                              Example VII-2                                           ______________________________________                                        Smoothness of Photoconductive Layer*.sup.3)                                                           500                                                   (sec/cc)                                                                      Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                              I (20° C., 65% RH)                                                                    680                                                            II (30° C., 80% RH)                                                                   670                                               D.R.R.       I (20° C., 65% RH)                                                                    90                                                (90 sec value) (%)                                                                         II (30° C., 80% RH)                                                                   87                                                E.sub.1/10 (erg/cm.sup.2)                                                                  I (20° C., 65% RH)                                                                    15                                                             II (30° C., 80% RH)                                                                   18                                                E.sub.1/100 (erg/cm.sup.2)                                                                 I (20° C., 65% RH)                                                                    23                                                             II (30° C., 80% RH)                                                                   27                                                Image Forming Performance                                                                I (20° C., 65% RH)                                                                  Very good                                                        II (30° C., 80% RH)                                                                 Very good                                             Contact Angle with Water*.sup.4) (°)                                                           10 or less                                            Printing Durability*.sup.5)                                                                           10,000 prints                                         ______________________________________                                    

The evaluation of each item shown in Table VII-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*4) Contact Anqle with Water

The light-sensitive material was passed once through an etchingprocessor using a solution prepared by diluting an oil-desensitizingsolution ELP-EX (produced by Fuji Photo Film Co., Ltd.) to a two-foldvolume with distilled water to conduct oil-desensitization treatment onthe surface of the photoconductive layer. On the thus oil-desensitizedsurface was placed a drop of 2 μl of distilled water, and the contactangle formed between the surface and water was measured using agoniometer.

*5) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment under the same condition as in *4) above. The resultinglithographic printing plate was mounted on an offset printing machine("Oliver Model 52" manufactured by Sakurai Seisakusho K. K.), andprinting was carried out on paper. The number of prints obtained untilbackground stains in the non-image areas appeared or the quality of theimage areas was deteriorated was taken as the printing durability. Thelarger the number of the prints, the higher the printing durability.

As can be seen from the results shown in Table VII-2, thelight-sensitive material according to the present invention had goodsurface smoothness, film strength and electrostatic characteristics ofthe photoconductive layer. The duplicated image obtained was clear andfree from background fog in the non-image area. These results appear tobe due to sufficient adsorption of the binder resin onto thephotoconductive substance and sufficient covering of the surface of theparticles with the binder resin. For the same reason, when it was usedas an offset master plate precursor, oil-desensitization of the offsetmaster plate precursor with an oil-desensitizing solution was sufficientto render the non-image areas satisfactorily hydrophilic, as shown by asmall contact angle of 10° or less with water. On practical printingusing the resulting master plate, 10,000 prints of clear image withoutbackground stains were obtained.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES VII-3 TO VII-18

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VII-2, except for using each ofResins (A) and Resins (B) shown in Table VII-3 below in place of Resin(A-104) and Resin (B-202) used in Example VII-2, respectively.

The electrostatic characteristics of the resulting light-sensitivematerials were evaluated in the same manner as described in ExampleVII-2. The results obtained are shown in Table VII-3 below.

                  TABLE VII-3                                                     ______________________________________                                                                                   E.sub.1/100                               Resin   Resin   V.sub.10                                                                            D.R.R.                                                                              E.sub.1/10                                                                            (erg/                              Example                                                                              (A)     (B)     (-V)  (%)   (erg/cm.sup.2)                                                                        cm.sup.2)                          ______________________________________                                        VII-3  A-103   B-203   610   82    27      41                                 VII-4  A-105   B-204   665   83    16      25                                 VII-5  A-109   B-205   630   83    18      27                                 VII-6  A-110   B-208   605   81    20      32                                 VII-7  A-111   B-210   600   80    21      33                                 VII-8  A-116   B-211   585   79    26      40                                 VII-9  A-119   B-212   680   84    17      26                                 VII-10 A-120   B-213   590   80    20      31                                 VII-11 A-121   B-215   670   81    18      25                                 VII-12 A-122   B-217   600   80    22      32                                 VII-13 A-125   B-219   645   81    17      24                                 VII-14 A-127   B-221   600   79    28      43                                 VII-15 A-128   B-222   685   84    18      25                                 VII-16 A-130   B-223   625   82    20      30                                 VII-17 A-131   B-224   600   80    21      33                                 VII-18 A-133   B-226   595   80    26      40                                 ______________________________________                                    

The electrostatic characteristics were evaluated under condition of 30°C. and 80% RH.

As a result of the evaluation on image forming performance of eachlight-sensitive material, it was found that clear duplicated imageshaving good reproducibility of fine lines and letters and no occurrenceof unevenness in half tone areas without the formation of background fogwere obtained. Further, when these electrophotographic light-sensitivematerials were employed as offset master plate precursors under the sameprinting condition as described in Example VII-2, more than 10,000 goodprints were obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty. Also, it can be seen that the electrostatic characteristicsare further improved by the use of the resin (A').

EXAMPLES VII-19 TO VII-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VII-1, except for using each of thedyes shown in Table VII-4 below in place of Cyanine Dye (VII-I) used inExample VII-1.

                                      TABLE VII-4                                 __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    VII-19                                                                             (VII-III)                                                                            ##STR406##                                                        VII-20                                                                             (VII-IV)                                                                             ##STR407##                                                        VII-21                                                                             (VII-V)                                                                              ##STR408##                                                        VII-22                                                                             (VII-VI)                                                                             ##STR409##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe condition of hightemperature and high humidity (30° C. and 80% RH).

EXAMPLES VII-23 AND VII-24

A mixture of 6.5 g of Resin (A-101) (Example VII-23) or Resin (A-128)(Example VII-24), 33.5 g of Resin (B-217), 200 g of zinc oxide, 0.02 gof uranine, 0.03 g of Methine Dye (VII-VII) shown below, 0.03 g ofMethine Dye (VII-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and300 g of toluene was dispersed by a homogenizer at a rotation of 7×10³r.p.m. for 10 minutes to prepare a coating composition for alight-sensitive layer. The coating composition was coated on paper,which had been subjected to electrically conductive treatment, by a wirebar at a dry coverage of 20 g/m², and dried for 20 seconds at 110° C.Then, the coated material was allowed to stand in a dark place for 24hours under the conditions of 20° C. and 65% RH to prepare eachelectrophotographic light-sensitive material. ##STR410##

COMPARATIVE EXAMPLE VII-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VII-23, except for using 33.5 g of Resin (R-VII-3)shown below in place of 33.5 g of Resin (B-217) used in Example VII-23.##STR411##

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example VII-2.The results obtained are shown in Table VII-5 below.

                                      TABLE VII-5                                 __________________________________________________________________________                                       Comparative                                                   Example VII-23                                                                        Example VII-24                                                                        Example VII-3                              __________________________________________________________________________    Binder Resin       (A-101)/(B-217)                                                                       (A-128)/(B-217)                                                                       (A-101)/(R-VII-3)                          Smoothness of Photoconductive                                                                    505     510     490                                        Layer (sec/cc)                                                                Electrostatic Characteristics*.sup.6)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                               615     690     585                                                 II (30° C., 80% RH)                                                              605     675     570                                        D.R.R. (%)                                                                             I (20° C., 65% RH)                                                               94      97      91                                                  II (30° C., 80% RH)                                                              91      95      89                                         E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                               9.5     7.4     11.4                                                II (30° C., 80% RH)                                                              10.1    8.0     12.0                                       E.sub.1/100 (lux/sec)                                                                  I (20° C., 65% RH)                                                               15.2    11.5    19.0                                                II (30° C., 80% RH)                                                              16.2    12.4    20.0                                       Image Forming*.sup.7)                                                                  I (20° C., 65% RH)                                                               Good    Very good                                                                             Edge mark of cutting                       Performance                                                                            II (30° C., 80% RH)                                                              Good    Very good                                                                             Edge mark of cutting,                                                         unevenness in half                                                            tone area                                  Contact Angle with Water (°)                                                              10 or less                                                                            10 or less                                                                            10 or less                                 Printing Durability                                                                              10,000  10,000  Background stain due to                                       prints  prints  edge mark of cutting                                                          occurred from the start                                                       of printing                                __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleVII-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*6) Measurement of Electrostatic Characteristics: E_(1/10) and E_(1/100)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 or 1/100 thereof was determined, and theexposure amount E_(1/10) or E_(1/100) (lux.sec) was calculatedtherefrom.

*7) Image Forminq Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine ELP-404V (manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I) or30° C. and 80% RH (II). The original used for the duplication wascomposed of cuttings of other originals pasted up thereon.

From the results shown above, it can be seen that each light-sensitivematerial exhibited almost same properties with respect to the surfacesmoothness and mechanical strength of the photoconductive layer.However, on the electrostatic characteristics, the light-sensitivematerial of Comparative Example VII-3 had the particularly large valueof photosensitivity E_(1/100), and this tendency increased under thehigh temperature and high humidity condition. On the contrary, theelectrostatic characteristics of the light-sensitive material accordingto the present invention were good. Further, those of Example VII-24using the resin (A') were very good. The value of E_(1/100) thereof wasparticularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example VII-3. On the contrary,the light-sensitive materials according to the present inventionprovided clear duplicated images free from background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative Example VII-3,the above described edge mark of cuttings pasted up was not removed withthe oil-desensitizing treatment and the background stains occurred fromthe start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention can only have excellentperformance.

EXAMPLE VII-25

A mixture of 5 g of Resin (A-122), 35 g of Resin (B-222), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengali 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example VII-24 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example VII-24, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH). Further, when the material was employed as an offset master plateprecursor, 10,000 prints of clear image were obtained.

EXAMPLES VII-26 TO VII-49

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VII-25, except for using 5 g of eachof Resin (A) and 35 g of each of Resin (B) shown in Table VII-6 below inplace of 5 g of Resin (A-122) and 35 g of Resin (B-222) used in ExampleVII-25, respectively.

                  TABLE VII-6                                                     ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        VII-26        A-101         B-206                                             VII-27        A-102         B-209                                             VII-28        A-104         B-210                                             VII-29        A-105         B-212                                             VII-30        A-109         B-213                                             VII-31        A-115         B-215                                             VII-32        A-120         B-217                                             VII-33        A-121         B-218                                             VII-34        A-122         B-219                                             VII-35        A-125         B-221                                             VII-36        A-126         B-225                                             VII-37        A-129         B-209                                             VII-38        A-103         B-202                                             VII-39        A-104         B-220                                             VII-40        A-107         B-209                                             VII-41        A-108         B-218                                             VII-42        A-112         B-203                                             VII-43        A-113         B-223                                             VII-44        A-114         B-221                                             VII-45        A-115         B-224                                             VII-46        A-126         B-205                                             VII-47        A-130         B-210                                             VII-48        A-132         B-214                                             VII-49        A-124         B-208                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionof high temperature and high humidity (30° C. and 80% RH). Further, whenthese materials were employed as offset master plate precursors, morethan 10,000 prints of a clear image free from background stains wereobtained respectively.

EXAMPLE VIII-1

A mixture of 6 g (solid basis) of Resin (A-203), 34 g (solid basis) ofResin (B-201), 200 g of photoconductive zinc oxide, 0.018 g of CyanineDye (VIII-I) shown below, 0.15 g of phthalic anhydride and 300 g oftoluene was dispersed by a homogenizer (manufactured by Nippon Seiki K.K.) at a rotation of 6×10³ r.p.m. for 8 minutes to prepare a coatingcomposition for a light-sensitive layer. The coating composition wascoated on paper, which had been subjected to electrically conductivetreatment, by a wire bar at a dry coverage of 25 g/m², followed bydrying at 110° C. for 10 seconds. The coated material was then allowedto stand in a dark place at 20° C. and 65% RH for 24 hours to prepare anelectrophotographic light-sensitive material. ##STR412##

COMPARATIVE EXAMPLE VIII-1

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VIII-1, except for using 34 g of Resin (R-VIII-1)shown below in place of 34 g of Resin (B-201) used in Example VIII-1.##STR413##

COMPARATIVE EXAMPLE VIII-2

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VIII-1, except for using 34 g of Resin (R-VIII-2)shown below in place of 34 g of Resin (B-201) used in Example VIII-1.##STR414##

With each of the light-sensitive material thus prepared, electrostaticcharacteristics and image forming performance were evaluated. Theresults obtained are shown in Table VIII-1 below.

                  TABLE VIII-1                                                    ______________________________________                                                   Ex-   Comparative Comparative                                                 ample Example     Example                                                     VIII-1                                                                              VIII-1      VIII-2                                           ______________________________________                                        Electrostatic*.sup.1)                                                         Characteristics                                                               V.sub.10 (-V)                                                                 I (20° C., 65% RH)                                                                  780     715         740                                          II (30° C., 80% RH)                                                                 765     690         720                                          III (15° C., 30% RH)                                                                785     720         750                                          D.R.R.                                                                        (90 sec value) (%)                                                            I (20° C., 65% RH)                                                                  88      83          86                                           II (30° C., 80% RH)                                                                 84      78          84                                           III (15° C., 30% RH)                                                                87      84          86                                           E.sub.1/10 erg/cm.sup.2)                                                      I (20° C., 65% RH)                                                                  22      30          26                                           II (30° C., 80% RH)                                                                 20      27          24                                           III (15° C., 30% RH)                                                                28      33          30                                           Image Forming*.sup.2)                                                         Performance                                                                   I (20° C., 65% RH)                                                                  Good    Good        Good                                         II (30° C., 30% RH)                                                                 Good    Unevenness in                                                                             Unevenness in                                                     half tone area                                                                            half tone area                               III (15° C., 30% RH)                                                                Good    White spots White spots                                                       in image por-                                                                             in image                                                          tion, slight                                                                              portion                                                           unevenness in                                                                 half tone area                                           ______________________________________                                    

The evaluation of each item shown in Table VIII-1 was conducted in thefollowing manner.

1 ) Electrostatic Characteristics

The light-sensitive material was charged with a corona discharge to avoltage of -6 kV for 20 seconds in a dark room using a paper analyzer("Paper Analyzer SP- 428" manufactured by Kawaguchi Denki K. K.). Tenseconds after the corona discharge, the surface potential V₁₀ wasmeasured. The sample was then allowed to stand in the dark for anadditional 90 seconds, and the potential V₁₀₀ was measured. The darkdecay retention rate (DRR; %), i.e., percent retention of potentialafter dark decay for 90 seconds, was calculated from the followingequation:

    DRR (%)=(V.sub.100 /V.sub.10)×100

Separately, the surface of photoconductive layer was charged to -400 Vwith a corona discharge and then exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm), and the time required for decay of the surface potential V₁₀ toone-tenth was measured, and the exposure amount E_(1/10) (erg/cm²) wascalculated therefrom. The measurements were conducted under ambientcondition of 20° C. and 65% RH (I), 30° C. and 80% RH (II) or 15° C. and30% RH (III).

*2) Image Forminq Performance

After the light-sensitive material was allowed to stand for one dayunder the ambient condition shown below, the light-sensitive materialwas charged to -6 kV and exposed to light emitted from agallium-aluminum-arsenic semi-conductor laser (oscillation wavelength:780 nm; output: 2.8 mW) at an exposure amount of 64 erg/cm² (on thesurface of the photoconductive layer) at a pitch of 25 μm and a scanningspeed of 300 m/sec. The thus formed electrostatic latent image wasdeveloped with a liquid developer ELP-T (produced by Fuji Photo FilmCo., Ltd.), washed with a rinse solution of isoparaffinic solvent IsoparG (manufactured by Esso Chemical K. K.) and fixed. The duplicated imageobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III).

As can be seen from the results shown in Table VIII-1, thelight-sensitive material according to the present invention exhibitedgood electrostatic characteristics and provided duplicated image whichwas clear and free from background fog, even when the ambient conditionwas fluctuated. On the contrary, while the light-sensitive materials ofComparative Examples VIII-1 and VIII-2 exhibited good image formingperformance under the ambient condition of normal temperature and normalhumidity (I), the occurrence of unevenness of density was observed inthe highly accurate image portions, in particular, half tone areas ofcontinuous gradation under the ambient condition of high temperature andhigh humidity (II) regardless of the electrostatic characteristics. Alsoa slight background fog remained without removing after the rinsetreatment. Further, the occurrence of unevenness of small white spots atrandom in the image portion was observed under the ambient condition oflow temperature and low temperature (III).

From all these considerations, it is thus clear that anelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and image formingperformance (in particular, for highly accurate image) and beingadvantageously employed particularly in a scanning exposure system usinga semiconductor laser beam can be obtained only using the binder resinaccording to the present invention.

EXAMPLE VIII-2

A mixture of 5 g (solid basis) of Resin (A-221), 35 g (solid basis) ofResin (B-202), 200 g of photoconductive zinc oxide, 0,020 g of MethineDye (VIII-II) shown below, 0.20 g of N-hydroxymaleinimide and 300 g oftoluene was treated in the same manner as described in Example VIII-1 toprepare an electrophotographic light-sensitive material. ##STR415##

COMPARATIVE EXAMPLE VIII-3

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VIII-2, except for using 35 g of Resin (R-VIII-3)shown below in place of 35 g of Resin (B-202) used in Example VIII-2.##STR416##

COMPARATIVE EXAMPLE VIII-4

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VIII-2, except for using 35 g of Resin (R-VIII-4)shown below in place of 35 g of Resin (B-202) used in Example VIII-2.##STR417##

With each of the light-sensitive materials thus-prepared, a filmproperty in terms of surface smoothness, mechanical strength,electrostatic characteristics and image forming performance wereevaluated. Further, printing property was evaluated when it was used asan electrophotographic lithographic printing plate precursor. Theresults obtained are shown in Table VIII-2 below.

                                      TABLE VIII-2                                __________________________________________________________________________                                Comparative                                                                            Comparative                                                  Example VIII-2                                                                        Example VIII-3                                                                         Example VIII-4                           __________________________________________________________________________    Smoothness of Photoconductive*.sup.3)                                                             400     330      405                                      Layer (sec/cc)                                                                Mechanical Strength of*.sup.4)                                                                    93      75       86                                       Photoconductive Layer (%)                                                     Electrostatic Characteristics                                                 V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                                765     725      745                                               II (30° C., 80% RH)                                                               750     700      720                                               III (15° C., 30% RH)                                                              770     730      745                                      D.R.R. (%)                                                                             I (20° C., 65% RH)                                                                89      85       87                                       (90 sec value)                                                                         II (30° C., 80% RH)                                                               84      80       82                                                III (15° C., 30% RH)                                                              88      86       86                                       E.sub.1/10 (erg/cm.sup.2)                                                              I (20° C., 65% RH)                                                                26      36       30                                                II (30° C., 80% RH)                                                               24      33       26                                                III (15° C., 30% RH)                                                              31      40       35                                       Image Forming                                                                          I (20° C., 65% RH)                                                                Good    Good     Good                                     Performance                                                                            II (30° C., 80% RH)                                                               Good    Unevenness in                                                                          Unevenness in                                                        half tone area                                                                         half tone area                                    III (15° C., 30% RH)                                                              Good    White spots in                                                                         White spots in                                                       image portion,                                                                         image portion                                                        unevenness in                                                                 half tone area                                    Water Retentivity of*.sup.5)                                                                      Good    Slight background                                                                      Background stain                         Light-Sensitive Material    stain                                             Printing Durability*.sup.6)                                                                       10,000 prints                                                                         4,000 prints                                                                           5,000 prints                             __________________________________________________________________________

The evaluation of each item shown in Table VIII-2 was conducted in thefollowing manner.

*3) Smoothness of Photoconductive Layer

The smoothness (sec/cc) of the light-sensitive material was measuredusing a Beck's smoothness test machine (manufactured by Kumagaya Riko K.K.) under an air volume condition of 1 cc.

*4) Mechanical Strength of Photoconductive Layer

The surface of the light-sensitive material was repeatedly (1000 times)rubbed with emery paper (#1000) under a load of 75 g/cm² using a Heidon14 Model surface testing machine (manufactured by Shinto Kagaku K. K.).After dusting, the abrasion loss of the photoconductive layer wasmeasured to obtain film retention (%).

*5) Water Retentivity of Light-Sensitive Material

A light-sensitive material without subjecting to plate making was passedtwice through an etching processor using an aqueous solution obtained bydiluting an oil-desensitizing solution ELP-EX (produced by Fuji PhotoFilm Co., Ltd.) to a five-fold volume with distilled water to conduct anoil-desensitizing treatment of the surface of the photoconductive layer.The material thus-treated was mounted on an offset printing machine("611XLA-II Model" manufactured by Hamada Printing Machine ManufacturingCo.) and printing was conducted using distilled water as dampeningwater. The extent of background stain occurred on the 50th print wasvisually evaluated. This testing method corresponds to evaluation ofwater retentivity after oil-desensitizing treatment of thelight-sensitive material under the forced condition.

*6) Printing Durability

The light-sensitive material was subjected to plate making in the samemanner as described in *2) above to form toner images, and the surfaceof the photoconductive layer was subjected to oil-desensitizationtreatment by passing twice through an etching processor using ELP-EX.The resulting lithographic printing plate was mounted on an offsetprinting machine ("Oliver Model 52", manufactured by Sakurai SeisakushoK. K.), and printing was carried out on paper. The number of printsobtained until background stains in the non-image areas appeared or thequality of the image areas was deteriorated was taken as the printingdurability. The larger the number of the prints, the higher the printingdurability.

As can be seen from the results shown in Table VIII-2, thelight-sensitive material according to the present invention had goodsurface smoothness, film strength and electrostatic characteristics ofthe photoconductive layer. The duplicated image obtained was clear andfree from background fog in the non-image area. These results appear tobe due to sufficient adsorption of the binder resin onto thephotoconductive substance and sufficient covering of the surface of theparticles with the binder resin. For the same reason, when it was usedas an offset master plate precursor, oil-desensitization of the offsetmaster plate precursor with an oil-desensitizing solution was sufficientto render the non-image areas satisfactorily hydrophilic and adhesion ofink was not observed at all as a result of the evaluation of waterretentivity under the forced condition. On practical printing using theresulting master plate, 10,000 prints of clear image without backgroundstains were obtained.

On the contrary, with the light-sensitive materials of ComparativeExamples VIII-3 and VIII-4, the occurrence of slight background stain innon-image area, unevenness in highly accurate image of continuousgradation and unevenness of white spots in image portion was observedwhen the image formation was conducted under severe conditions. Further,as a result of the test on water retentivity of these light-sensitivematerials to make offset master plates, the adhesion of ink wasobserved. The printing durability thereof was at most from 4,000 to5,000 prints.

From these results it is believed that the resin (A) and the resin (B)according to the present invention suitably interacts with zinc oxideparticles to form the condition under which an oil-desensitizingreaction proceeds easily and sufficiently with an oil-desensitizingsolution and that the remarkable improvement in film strength isachieved by the action of the resin (B).

EXAMPLES VIII-3 TO VIII-22

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VIII-2, except for using each ofResins (A) and Resins (B) shown in Table VIII-3 below in place of Resin(A-221) and Resin (B-202) used in Example VIII-2, respectively.

                  TABLE VIII-3                                                    ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        VIII-3        A-205         B-203                                             VIII-4        A-206         B-204                                             VIII-5        A-207         B-205                                             VIII-6        A-208         B-206                                             VIII-7        A-209         B-208                                             VIII-8        A-210         B-209                                             VIII-9        A-211         B-211                                             VIII-10       A-213         B-212                                             VIII-11       A-214         B-216                                             VIII-12       A-215         B-219                                             VIII-13       A-216         B-220                                             VIII-14       A-218         B-221                                             VIII-15       A-221         B-222                                             VIII-16       A-222         B-223                                             VIII-17       A-223         B-224                                             VIII-18       A-221         B-225                                             VIII-19       A-211         B-226                                             VIII-20       A-207         B-215                                             VIII-21       A-204         B-214                                             VIII-22       A-214         B-218                                             ______________________________________                                    

The electrostatic characteristics and image forming; performance of eachof the light-sensitive materials were determined in the same manner asdescribed in Example VIII-1. Each light-sensitive material exhibitedgood electrostatic characteristics. As a result of the evaluation onimage forming performance of each light-sensitive material, it was foundthat clear duplicated images having good reproducibility of fine linesand letters and no occurrence of unevenness in half tone areas withoutthe formation of background fog were obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example VIII-2, more than 10,000 good printswere obtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics and printingproperty.

EXAMPLES VIII-23 TO VIII-26

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VIII-1, except for using each of thedyes shown in Table VIII-4 below in place of Cyanine Dye (VIII-I) usedin Example VIII-1.

                                      TABLE VIII-4                                __________________________________________________________________________    Example                                                                            Dye   Chemical Structure of Dye                                          __________________________________________________________________________    VIII-23                                                                            (VIII-III)                                                                           ##STR418##                                                        VIII-24                                                                            (VII-IV)                                                                             ##STR419##                                                        VIII-25                                                                            (VIII-V)                                                                             ##STR420##                                                        VIII-26                                                                            (VIII-VI)                                                                            ##STR421##                                                        __________________________________________________________________________

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided clear duplicated images free frombackground fog even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH) and low temperatureand low humidity (15° C. and 30% RH).

EXAMPLES VIII-27 AND VIII-28

A mixture of 6.5 g of Resin (A-201) (Example VIII-27) or Resin (A-207)(Example VIII-28), 33.5 g of Resin (B-223), 200 g of zinc oxide, 0.02 gof uranine, 0.03 g of Methine Dye (VIII-VII) shown below, 0.03 g ofMethine Dye (VIII-VIII) shown below, 0.18 g of p-hydroxybenzoic acid and300 g of toluene was dispersed by a homogenizer at a rotation of 7×10³r.p.m. for 6 minutes to prepare a coating composition for alight-sensitive layer. The coating composition was coated on paper,which had been subjected to electrically conductive treatment, by a wirebar at a dry coverage of 25 g/m², and dried for 20 seconds at 110° C.Then, the coated material was allowed to stand in a dark place for 24hours under the conditions of 20° C. and 65% RH to prepare eachelectrophotographic light-sensitive material. ##STR422##

COMPARATIVE EXAMPLE VIII-5

An electrophotographic light-sensitive material was prepared in the samemanner as in Example VIII-27, except for using 33.5 g of Resin(R-VIII-2) used in Comparative Example VIII-2 in place of 33.5 g ofResin (B-223) used in Example VIII-27.

With each of the light-sensitive materials thus prepared, variouscharacteristics were evaluated in the same manner as in Example VIII-2.The results obtained are shown in Table VIII-5 below.

                                      TABLE VIII-5                                __________________________________________________________________________                        Example Example Comparative                                                   VIII-27 VIII-28 Example VIII-5                            __________________________________________________________________________    Binder Resin        (A-201)/(B-223)                                                                       (A-207)/(B-223)                                                                       (A-201)/(R-VIII-2)                        Smoothness of Photoconductive                                                                     380     400     385                                       Layer (sec/cc)                                                                Mechanical Strength of                                                                            93      94      87                                        Photoconductive Layer (%)                                                     Electrostatic Characteristics*.sup.7)                                         V.sub.10 (-V)                                                                          I (20° C., 65% RH)                                                                580     740     550                                                II (30° C., 80% RH)                                                               565     725     540                                                III (15° C., 30% RH)                                                              585     740     550                                       D.R.R. (%)                                                                             I (20° C., 65% RH)                                                                88      95      83                                                 II (30° C., 80% RH)                                                               85      93      80                                                 III (15° C., 30% RH)                                                              89      95      84                                        E.sub.1/10 (lux/sec)                                                                   I (20° C., 65% RH)                                                                13.3    8.9     14.5                                               II (30° C., 80% RH)                                                               13.5    8.5     13.7                                               III (15° C., 30% RH)                                                              14.2    9.6     14.9                                      Image Forming*.sup.8)                                                                  I (20° C., 65% RH)                                                                Good    Very good                                                                             Edge mark of cutting                      Performance                                                                            II (30° C., 80% RH)                                                               Good    Very good                                                                             Unevenness in half                                                            tone area                                          III (15° C., 30% RH)                                                              Good    Very good                                                                             White spots in image                                                          portion, unevenness in                                                        half tone area                            Water Retentivity of                                                                              Good    Good    Slight background stain                   Light-Sensitive Material                                                      Printing Durability 10,000 prints                                                                         10,000 prints                                                                         4,000 prints                              __________________________________________________________________________

The characteristics were evaluated in the same manner as in ExampleVIII-2, except that some electrostatic characteristics and image formingperformance were evaluated according to the following test methods.

*7) Electrostatic Characteristics: E_(1/10)

The surface of the photoconductive layer was charged to -400 V withcorona discharge, and then irradiated by visible light of theilluminance of 2.0 lux. Then, the time required for decay of the surfacepotential (V₁₀) to 1/10 thereof was determined, and the exposure amountE_(1/10) (lux.sec) was calculated therefrom.

*8) Image Forming Performance

The electrophotographic light-sensitive material was allowed to standfor one day under the ambient condition described below, thelight-sensitive material was subjected to plate making by afull-automatic plate making machine ELP-404V (manufactured by Fuji PhotoFilm Co., Ltd.) using ELP-T as a toner. The duplicated image thusobtained was visually evaluated for fog and image quality. The ambientcondition at the time of image formation was 20° C. and 65% RH (I), 30°C. and 80% RH (II) or 15° C. and 30% RH (III). The original used for theduplication was composed of cuttings of other originals pasted upthereon.

From the results, it can be seen that each of the light-sensitivematerials according to the present invention exhibited good mechanicalstrength of the photoconductive layer. On the contrary, with thelight-sensitive material of Comparative Example VIII-5 the value ofmechanical strength was lower than them, and the value of E_(1/10) ofelectrostatic characteristics degraded particularly under the ambientcondition of low temperature and low humidity (III), while they weregood under the ambient condition of normal temperature and normalhumidity (I). On the other hand, the electrostatic characteristics ofthe light-sensitive materials according to the present invention weregood. Particularly, those of Example VIII-28 using the resin (A') werevery good. The value of E_(1/100) thereof was particularly small.

With respect to image forming performance, the edge mark of cuttingspasted up was observed as background fog in the non-image areas in thelight-sensitive material of Comparative Example VIII-5. Also theoccurrence of unevenness in half tone area of continuous gradation andunevenness of small white spots in image portion was observed on theduplicated image when the ambient conditions at the time of the imageformation were high temperature and high humidity (II) and lowtemperature and low humidity (III). On the contrary, the light-sensitivematerial according to the present invention provided clear images freefrom background fog.

Further, each of these light-sensitive materials was subjected to theoil-desensitizing treatment to prepare an offset printing plate andusing the resulting plate printing was conducted. The plates accordingto the present invention provided 10,000 prints of clear image withoutbackground stains. However, with the plate of Comparative ExampleVIII-5, the above described edge mark of cuttings pasted up was notremoved with the oil-desensitizing treatment and the background stainsoccurred from the start of printing.

It can be seen from the results described above that the light-sensitivematerials according to the present invention was satisfactory in allaspects of the surface smoothness and film strength of thephotoconductive layer, electrostatic characteristics and printingproperty. Further, it can be seen that the electrostatic characteristicsare further improved by the use of the resin (A').

EXAMPLE VIII-29

A mixture of 5 g of Resin (A-223), 35 g of Resin (B-222), 200 g of zincoxide, 0.02 g of uranine, 0.04 g of Rose Bengal, 0.03 g of bromophenolblue, 0.40 g of phthalic anhydride and 300 g of toluene was treated inthe same manner as described in Example VIII-27 to prepare anelectrophotographic light-sensitive material.

As the result of the evaluation of various characteristics in the samemanner as described in Example VIII-27, it can be seen that thelight-sensitive material according to the present invention is excellentin charging properties, dark charge retention rate and photosensitivity,and provides a clear duplicated image free from background fog undersevere conditions of high temperature and high humidity (30° C. and 80%RH) and low temperature and low humidity (15° C. and 30% RH). Further,when the material was employed as an offset master plate precursor,10,000 prints of clear image were obtained.

EXAMPLES VIII-30 TO VIII-53

Each electrophotographic light-sensitive material was prepared in thesame manner as described in Example VIII-29, except for using 5 g ofeach of Resin (A) and 35 g of each of Resin (B) shown in Table VIII-6below in place of 5 g of Resin (A-223) and 35 g of Resin (B-222) used inExample VIII-29, respectively.

                  TABLE VIII-6                                                    ______________________________________                                        Example       Resin (A)     Resin (B)                                         ______________________________________                                        VIII-30       A-202         B-206                                             VIII-31       A-203         B-207                                             VIII-32       A-204         B-208                                             VIII-33       A-205         B-209                                             VIII-34       A-206         B-211                                             VIII-35       A-207         B-212                                             VIII-36       A-208         B-213                                             VIII-37       A-209         B-214                                             VIII-38       A-210         B-215                                             VIII-39       A-211         B-216                                             VIII-40       A-212         B-218                                             VIII-41       A-213         B-217                                             VIII-42       A-214         B-220                                             VIII-43       A-215         B-221                                             VIII-44       A-216         B-222                                             VIII-45       A-217         B-223                                             VIII-46       A-218         B-224                                             VIII-47       A-219         B-226                                             VIII-48       A-220         B-222                                             VIII-49       A-221         B-222                                             VIII-50       A-222         B-204                                             VIII-51       A-218         B-205                                             VIII-52       A-223         B-203                                             VIII-53       A-223         B-223                                             ______________________________________                                    

Each of the light-sensitive materials according to the present inventionwas excellent in charging properties, dark charge retention rate andphotosensitivity, and provided a clear duplicated image free frombackground fog and scratches of fine lines even under severe conditionsof high temperature and high humidity (30° C. and 80% RH) and lowtemperature and low humidity (15° C. and 30% RH). Further, when thesematerials were employed as offset master plate precursors, 10,000 printsof a clear image free from background stains were obtained respectively.

POSSIBILITY OF UTILIZATION IN INDUSTRY

In accordance with the present invention, an electrophotographiclight-sensitive material which exhibits excellent electrostaticcharacteristics (particularly, under severe conditions) and mechanicalstrength and provides clear images of good quality can be obtained. Theelectrophotographic light-sensitive material according to the presentinvention is particularly useful in the scanning exposure system using asemiconductor laser beam. The electrostatic characteristics are furtherimproved by using the resin according to the present invention whichcontains a repeating unit having the specific methacrylate component.

What is claimed is:
 1. An electrophotographic light-sensitive materialhaving a photoconductive layer containing at least an inorganicphotoconductive substance, a spectral sensitizing dye, and a binderresin, wherein the binder resin comprises at least one resin (A) shownbelow and at least one resin (B) shown below:Resin (A): a resin having aweight average molecular weight of from 1×10³ to 2×10⁴ and containingnot less than 30% by weight of a polymer component corresponding to arepeating unit represented by the general formula (I) described belowand from 0.5 to 15% by weight of a polymer component containing at leastone polar group selected from the group consisting of --PO₃ H₂, --SO₃ H,--COOH, ##STR423## wherein R¹ represents a hydrocarbon group or --OR²,and wherein R² represents a hydrocarbon group, and a cyclic acidanhydride-containing group; ##STR424## wherein a¹ and a² each representsa hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group,--COOR⁴ or --COOR⁴ bonded via a hydrocarbon group, wherein R⁴ representsa hydrocarbon group, and R³ represents a hydrocarbon group;Resin (B): alinear AB block copolymer having a weight average molecular weight offrom 3×10⁴ to 1×10⁶ and comprising an A block comprising a polymercomponent containing at least one polar group selected from the groupconsisting of specific polar groups as described in the resin (A) aboveand a B block comprising a polymer component represented by the generalformula (I) as described in the resin (A) above, wherein the A blockcontains the polymer component containing the polar group in an amountof from 0.05 to 10% by weight based on the copolymer and the B blockcontains the polymer component represented by the general formula (I) inan amount not less than 30% by weight based on the copolymer.
 2. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein the resin (A) contains, as the polymer component represented bythe general formula (I), at least one methacrylate component having anaryl group represented by at least one of the following general formulae(Ia) and (Ib): ##STR425## wherein T₁ and T₂ each represents a hydrogenatom, a halogen atom, a hydrocarbon group having from 1 to 10 carbonatoms, --COR_(a) or --COOR_(a) wherein R_(a) represents a hydrocarbongroup having from 1 to 10 carbon atoms; and L₁ and L₂ each represents amere bond or a linking group containing from 1 to 4 linking atoms, whichconnects --COO-- and the benzene ring.
 3. An electrophotographiclight-sensitive material as claimed in claim 1, wherein the total amountof the specific polar group-containing polymer component contained inthe resin (B) is from 10 to 50% by weight based on the total amount ofthe specific polar group-containing polymer component present in theresin (A).
 4. An electrophotographic light-sensitive material as claimedin claim 1, wherein the polar group-containing polymer component ispresent in the polymer chain of the resin (A).
 5. An electrophotographiclight-sensitive material as claimed in claim 4, wherein the polargroup-containing polymer component is present at random in the resin(A).
 6. An electrophotographic light-sensitive material as claimed inclaim 4, wherein the polar group-containing polymer component is presentin the form of a block in the resin (A).
 7. An electrophotographiclight-sensitive material as claimed in claim 1, wherein the polargroup-containing polymer component is present at one terminal of thepolymer chain of the resin (A).
 8. An electrophotographiclight-sensitive material as claimed in claim 1, wherein the polargroup-containing polymer component is present both in the polymer chainand at the terminal of the polymer chain of the resin (A).
 9. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein the resin (B) is an AB block copolymer wherein the A block andthe B blocks are bonded to each other as follows: (A block)-b-(B block),wherein b represents a bond connecting two blocks present on both sides.10. An electrophotographic light-sensitive material as claimed in claim1, wherein the resin (B) is an AB block copolymer wherein the polargroup-containing polymer component is bonded at one terminal of the Ablock and the opposite terminal of the A block is bonded to the B blockas follows: (Polar Group)-(A block)--b--(B block), wherein b representsa bond connecting two blocks present on both sides.
 11. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein the resin (B) is an AB block copolymer wherein a B block isbonded at one terminal of the A block and another B block is bonded atthe other terminal of the A block as follows: (B block)--b--(Ablock)--b--(B block), wherein b represents a bond connecting two blockspresent on both sides.